I know that allot of folks didn't care for the recordings of our class being posted on the website for everyone to listen to but I think it would be a good tool in becoming a better player. I think it may even be good to have them video taped. One thing I've noticed is that it helps to be aware of the rest of the group when performing our songs. Some people, including myself, concentrate so much on their lead break that we loose track of everyone else (the rhythm) and it takes away from the dynamic of the song. It would help me if I could look back on these performances to see where I went wrong and could improve.
I think a sound recording of the music in class is fine and is second only to playing in person. With a recording you can try stretching your abilities and don't get to feel nearly as bad if you don't get it right.
On the other hand, as an internet user, I am 100% opposed to video because of the ease with which it can get out of your control into the world of youtube and beyond. I feel almost the same about vocals. They also can get out of your control and have little value to people trying to improve their playing.
So, for me, I am 100% in favor of recording instrumental music in class for class use. I am 100% opposed to video and am not too keen on vocal music.