Our default crawler obeys robots.txt and it looks like the /results URLs are not allowed. However.. I think you could start from a URL like http://www.youtube.com/watch?v=sAzhOSbxMiI and then crawl to the linked videos from there...
Oh I didn't know about the robots.txt rule for /results. Thanks for pointing it out or I would have built my own crawler and got banned. I think I'll go with playlists.