Is it good or bad that educators do not control the periphery of a website like youtube - i.e. what effect does advertising and the interest of the .com have on the use of the content?

And while the sharing of web2.0 videos/photos is condoned by the sites themselves, does this cause a bridge or reliance between educators and content providers? For instance, A student or I use a video to explain something - I can’t/don’t copy it from a video sharing website. The author changes or deletes the video. What now?