Half are commercial. Search for (Acura) RDX and see how many dealership commerical comes up. There are many good clips on the internet but 95% of all Youtube video are pure crap that should be deleted after 6 months or something.
Nice illustration of the information overload: If you watch YouTube videos nonstop without sleep or bathroom breaks, you still miss out on almost 4 years of material every 24 hours.
Which is why you need crowdsourcing, recommendations and whatnot just in order to find the relatively few videos you might be interested in watching, you don't stand a chance finding them on your own.
TV does make it easier: The number of possible choices aren't quite that overwhelming, you already have a fair idea of whether you would like Disney or Discovery Channel, and you know where to find the next episode of Lost or The Daily Show.
I don't think YouTube will outcompete cable TV. But chat, Facebook and Hulu might.
youtube is no different from the web or TV. I'm not interested in 99% of what's on any of them. I love youtube because it's allowed me to see things that don't get on TV, RC flying, close harmony vocal jazz, motorcycle skill videos, Hilary Hahn, Jeff Dunham, Connie Talbot, Sungha Jung, Narciso Yepes and on it goes. I'll probably watch TV again the next time somebody lands on the moon.