I tried to use google custom Search Engine (cse) to search in a specific video sharing websites (like: youtube, Y! video, ... etc). The idea is that a user enters a keyword. then, the results are fetched from those predefined websites. Is it possible to do that? Or those kind of video sharing websites prevent queries from outside?
That is what Google Custom Search is for.
Set your sites to:
*.youtube.com/*
video.yahoo.com/*
That's it.
I just did exactly this and it works fine - here is my test search.