There are three other marching reaction video sources I enjoy:
Adam Tan (https://www.youtube.com/channel/UCb1UI8X57325r8zS1fI7uUw) - A percussionist and composer from Australia who hosts a regular show on YouTube. One of his segments is "Let's Watch" where he checks out and reacts to videos submitted by his audience. Some time ago, somebody submitted DCI videos, something Adam had never seen before because there is absolutely no marching activities in Australia. Adam got hooked, has been checking out a bunch of other videos submitted to him, and has talked about coming to DCI and possibly checking out BOA since it takes place during the same time as PASIC in Indy.
Funliner Productions (https://www.youtube.com/channel/UCAvzRkdZUrZgoo4-4yiuzpQ) - A group of drum corps alum who interview other performers, as well as marching videos such as head cams and reaction videos of shows they admire or were a part of. One such video was the head cam of Ben Gunderson, the flugel soloist from 2016 Bluecoats, and included his commentary along with the reaction of the hosts.
EMCproductions (https://www.youtube.com/user/underwatrdrummr) - This guy aged out with Carolina Crown in 2010, marched with United Percussion in WGI, and also marched with the Marine D&BC. He likes to do themes like "No Tick November" which celebrates incredibly clean performances (2009 Rhythm X was one such show, in fact), and also extends to some fun concepts such as learning the solos which beat him at I&E. 😄