YouTube is another one of those "I am not primarily a visual learner" things - I have seen a number of videos I find amusing, but in general, I'm more likely to spend 5 minutes reading an amusing blog post or two, or a book, or whatever, than watching a video.
For library purposes, we also discourage the use of YouTube on the school server's: the bandwidth hit is just too heavy, and slows down access for everyone else. (This is complicated by our network set-up: our high school grades are in Minneapolis, but our connection to the rest of the 'Net runs through via the main campus in Hopkins, so everything goes from here, to there, to the rest of the world. That connection also includes everything from email to the library databases to general internet access.)
That means that posting a YouTube (or other) video for library purposes doesn't make a whole lot of sense, though teachers do occasionally reference them specifically in class.
It took me a while to find a video that I thought might be interesting in this setting - for those of you who remember playing Tetris back when, this is a human version of it. I find it fascinating both because of the design planning needed, but because of the effect of taking an initially computer done project, and twisting it (and in this case, humanising it to some degree). Plus, it is also just fun to watch.