searching youtube video

How do I search for "python tutorial" videos on youtube? I get a lot of unrelated search results. What I need to know is the list of the users who have uploaded python related videos those are more than 20 minutes long.

Update:

In other words I need to scrap the following URL and find the unique users, for e.g. by PythonItalia

http://www.youtube.com/results?search_type=videos&search_category=28&search_duration=long&search_query=title%3Apython&page=10

Does it support NOT operator? so that I can exclude a user or category?