Not necessarily, well they do very much the same thing, however the content can be very different. YouTube tends to be much quicker at dealing with copyright infringement take downs, although Youku tends to be becoming somewhat better in this respect. There's very little Star Trek on Youku these days, and many more Chinese things on there of course. I use both, I get a lot of teaching materials from Youku, however there's many things I like to watch that are only on YouTube.
You are using Google and not Baidu? There's no reason why Google should be sending you to Youku rather than their own service, unless it's something that's only on Youku, or as been suggested something has hijacked your browser?
