In the sanitized North Vietnamese version, the Propaganda Unit for National Liberation was the ancestor of the regular NVA (PAVN). In part, this is true. But, the PUNL's more "irregular" activities, such as purges and targeted killings, are ignored - as in this July 2013 article, Meeting a fighter of the Armed Propaganda Unit for National Liberation:

PANO – Under the instruction of General Phung Quang Thanh, Minister of National Defence, a delegation of the Military History Institute of Vietnam, led by its director, Lieu. Gen. Vu Quang Dao, visited To Van Cam, one among 34 fighters of the Armed Propaganda Unit for National Liberation, the predecessor of the Vietnam People’s Army. ...
The "irregular" role is more accurately depicted in this article, The Armed Propaganda Teams of Vietnam:

This article will discuss the Armed Propaganda Teams of the Government of Vietnam in depth. Curiously, the terms “Armed Propaganda Team” or “APT” was first used by the Communist Government of North Vietnam, and later borrowed by the anti-Communist South who saw that it was a concept that worked.

Long before the Americans came upon the scene in Vietnam, the Indochinese Communist Party formed Armed Propaganda Teams called Doi Tuyen truyen Vo trang. General Vo Nguyen Giap, the man who would later become the hero of Dien Bien Phu in 1953 served as a Team Leader at one point in his career. Although both Uncle Ho and General Giap are given credit for the teams, it appears that Ho wrote the idea down on the back of a pack of cigarettes during the First Revolutionary Party Military Conference in September 1944 and General Giap brought the idea to fruitition. The units had the ability to fight if threatened by the enemy. Otherwise, they would do recruitment, propaganda plays and skits, and organize and mobilize the villages in the Communist cause. On 22 December 1944 Giap formed the First Armed Propaganda Brigade consisting of three teams with a total of 34 people called the Tran Hung Doa Platoon. The unit was armed with one machine gun, 31 rifles and 2 revolvers. That same month Ho Chi Minh created the “Vietnamese People's Propaganda Unit for National Liberation,” which became the People's Army of Vietnam (PAVN) in September 1945. After the Japanese conceded defeat on 16 August 1945, Armed Propaganda Teams spread the news across the country.
and

According to Forrest E. Morgan in Big Eagle, Little Dragon: Propaganda and the Coercive use of Airpower against North Vietnam:

Nearly all Communist military plans and directives for South Vietnam included lengthy instructions for producing and disseminating propaganda materials to reorient liberated citizens.
and

Robert Munshower served with 95th Military Police Battalion in Bien Hoa during 1967 to 1968. He told me:

The armed propaganda teams traveled from hamlet to hamlet presenting dramatized plays usually based on historical events but altered in theme to reflect the communist line and to legitimize the invasion of the South. These drama teams also entertained North Vietnamese Army units in the areas that they performed in. Propaganda, Proselytizing, and Drama teams brought the latest news, albeit distorted, invented and modified to fit the official party line emanating from Hanoi. The photos of a North Vietnamese Armed Propaganda Team in the Field are originals that I purchased from an employee of The Museum of The Revolution in Hanoi.
He adds:

A former Government of Vietnam Army Captain told me that when many of the drama and music teams were captured, the groups usually had a very high number of homosexual males, which just goes to show how committed the communists were to winning the war. They used every resource, including gays, to the maximum.
and

It is probably correct to say that almost any nighttime visitation of Viet Cong into a village was preceded by an armed propaganda team that explained the Communist cause and prepared the people to meet the needs of the combat forces. The enemy Armed Propaganda Team could move about within the village and pass as farmers or tradesmen. For instance, David Hunt mentions the APTs in an article entitled Villagers at War: The National Liberation Front In My Tho Province, 1965-1967. Some of his comments are:

Government of Vietnam cadres only came into the hamlets when it was convenient for them to do so, while (Communist) Front cadres who operated openly - that is, who possess legal papers, whose National Liberation Front affiliation is secret - seem to live within the community. The situation in the villages is relatively favorable to the Saigon regime in that the local Front organization cannot function above ground during the day, and Saigon’s “Armed Propaganda Teams" (the idea for such teams, including the name itself, is borrowed directly from the NLF) and regular troops can move around without fear of being hit hard by guerrillas or other NLF units.
There is much, much more in the article - on both the PAVN teams and the ARVN counter-teams.

The last quoted David Hunt article is still linked on the Vietnam webpage of Grover Furr of Montclair State Univ. (who still defends Stalin), as reviewed by Furr:

Villagers at War: The National Liberation Front In My Tho Province, 1965-1967, by David Hunt. One of the two or three foremost American experts on Vietnam, Hunt published this book as a special issue of Radical America in 1974. It has been long out of print and unavailable.

Ever since I read it some years ago, I've found this work very inspiring -- in fact, matched by few if any other works I can think of. It's based upon RAND Corp. interrogations of Vietnamese peasants -- POWs (i.e. members of the NLF), Communist Party members, 'deserters' who fled to the US/South Vietnamese side, and just plain villagers. The quotations from these interrogations are wonderful! They show how the Communist movement won tremendous respect from the Vietnamese peasants, by standing up for the poor and middle peasants; opposing the landlords and their murderous government; fought sexism; and organized young and old, male and female, to build communist relations while in the midst of a horrendously murderous military assault by American forces.
Hunt's BLUF is less polemical:

INTRODUCTION - A LOCAL STUDY OF THE NLF

Our knowledge of a generation of war in Vietnam is strikingly uneven. On the one hand, eye-witness accounts from veterans, books and newspaper reports, Watergate related disclosures and the Pentagon Papers, have given us a picture of American involvement in Indochina all the way back to 1946. But at the same time, we still know very little about the other side, the Viet Minh and the National Liberation Front (NLF) of South Vietnam. This is an essay about the NLF in My Tho Province. It deals with the years 1965 to 1967 when the United States tried and failed through large-scale military action to crush the insurgents in the South.

By concentrating on this Mekong Delta Province, I hope [p.4 ] to show what U. S. escalation meant in a specific locale, and how Front cadres (1) resisted the ambitious American campaign to destroy the movement they had built. ...

NLF leaders have always stressed the interdependence of military and political activity within the guerrilla movement. Still, in practice these two facets of the insurgency are clearly distinguishable. There is a great deal of information available on NLF military units, on the strategy and tactics of guerrilla warfare, on problems of supply, fortification, recruitment and training of soldiers. At the same time, many of our informants are peasants who had served the Front in hamlets and villages, and their recollections provide us with a unique opportunity to observe the "civilian" side of the movement at this grassroots level. In the following pages, I am concerned with the work of local cadres who supported the war effort from their posts in the rural communities of My Tho. In other words, our subject is the political aspects of NLF resistance to U. S. intervention.

My analysis rests on material drawn from the RAND Corporation's "Viet Cong Motivation and Morale'" project, conducted in Vietnam from 1964 to 1969. Designed under Pentagon sponsorship to explore strengths and weaknesses of the NLF, the project consisted of interviews with prisoners of war and with defectors from guerrilla ranks who sought refuge in the Chieu Hoi ("Open Arms") program of the Saigon Government. The interviews are organized by topic, one of which is : "Activities of the Viet Cong Within Dinh Tuong Province." Covering the period from 1965 to January 1968, the "DT" sequence of interviews is the only [p.5] series in the RAND project to focus on a single province.
IMO: All of this reinforces some (perhaps, all) of Bill Moore's points.

Regards

Mike