Good idea. I'm also worried about the increased chance of trolling / false editing that results from Youtube links. But I doubt Wikipedia is ready to or wants to be this involved in collaborating with any for-profit.
If the browser sends the referer, Wikipedia will be able to figure out themselves which pages YouTube points to. Then it won't be such much intentional collaboration, but instead damage control to prevent vandalism. I doubt Wikipedia is going to like doing that, but they don't have many other options.