I have several friends who end up doing informal social media consulting for various large companies. In relating their conversations with top brands and media co's, several were still trying to get a handle on their YouTube strategy and a few were holding off experimenting until they had "figured it out." Holy cow, the only way you learn about this stuff is by doing.
And digging a little deeper I heard that it wasn't just YouTube but many other consumer experience (social networks, twitter, flickr, virtual worlds, etc) that still confounded these larger companies.
Ok, obviously i'm biased here given my SecondLife/Google/YouTube background but people, if you don't understand and experiment you are very likely to miss opportunities. Or at least end up paying inflated amounts to digital agencies and consultants who don't know anything you can't figure out for yourself.
Here's my advice - and i think it makes sense for companies of every size - if you don't know how the Top 20 consumer websites can help or hurt your business then you are behind. You don't necessarily need to be participating in all of them but you should have a general understanding and hypothesis about how you might get involved. Then prioritize your experiments and get to work!