The Army, proving once again, that it doesn't understand how to recruit, retain and develop junior Officers.
I’d argue that this commercial is a step in the right direction, at least marketing wise. Actual recruitment/applicant processing/ candidate mentorship is a different story.

I'm not really sure what specific demographic they had in mind as this method seems to be aimed at people who don't have USMA, OCS, or ROTC available as an option to them
It’s aimed at everybody: high schoolers, college students and grads since the commercial made a point of showing soldiers in OCS, ROTC and WP gear.

(as each have their own robust recruiting for their target demographic).
I disagree with you here. The Army doesn’t do nearly enough to recruit for OCS at least it didn’t about a year ago when I was researching the subject. A majority of teens and 20 or 30 year olds don’t know the difference between enlisted and officer, much less the different officer accession routes, especially OCS. Even if they knew, they are likely to encounter an enlisted recruiter who will try to tell them they have to enlist and serve first in order to become an officer.

I’ve always been skeptical of the argument that the Officer Corps is in direct competition with Corporate America for college graduates – they’re in direct competition with college admissions and enlisted recruitment as the choice to use ROTC or USMA is made back in high school.
The choice to apply for the USMA is made back in high school. Cadets decide to join the ROTC at different times; some before college, other during their freshman, sophomore or even later years.

The notion that there is the untapped pool of people who passed up multiple chances to serve their country, but since earning a degree are just waiting for someone to ask if they want to be an Officer, is flat out silly.
How is it silly? I can’t find the PDF at the moment and the Marine Officer site has been changed but there was a breakdown of all the USMC commissioning sources and I’d say about 20% were OCC graduates (people who already have degree in hand).