For a list of top video sahring sites, check the site in the sig, and more specifically http://www.ilikesharingvideos.com/video-sharing-sites/en/sort-by-rank/ which lists them by Alexa rank. If you want a specific niche, you can use this page (http://www.ilikesharingvideos.com/video-sharing-sites/en/sort-by-niche/) to select the niche and sort it afterwards.