Here are my thoughts:
Firstly, YouTube can be easily watched with all free software
(https://trisquel.info/en/wiki/play-videos-without-using-flash) especially
since they are converting all their videos to webM. So the flash part is
quickly becoming irrelevant.
I have a similar channel
(http://www.youtube.com/user/LibreSoftware?feature=mhee) where I post Free
Software videos. I am not against the idea of a Trisquel YouTube channel.
It is on our roadmap (https://trisquel.info/en/wiki/roadmap) to expand the
community on certain social network type sites.
However, making those sorts of videos takes a lot of time and work. There
are lots of ways to help the project (https://trisquel.info/en/wiki/how-help)
and this seems like one of the bigger/harder tasks because of all the work
required to make those sort of videos. I'm not trying to discourage you
because if you can do the work that would be excellent but you may want to
start smaller and work your way up to an idea like that later.
P.S. If you have any Free Software videos you want me to put on my channel
let me know.