Seconded, and you also simply will not reach everyone with video.
I say go ahead and use Youtube, and as xhtmlcoder suggested put a transcript up for the people who can't access the video.
Besides, when it comes to things like lectures or roundtable discussions, I personally would rather read a transcript than sit through some slow video where I'm screaming "For crying out loud, get to the point!" (just with more profanity)
See why I can't STAND video tutorials.