as mean as it may be you can always reject a run if the video is not hosted on youtube, twitch, niconico or something well known. there is hardly ever a reason for the runner to be unable to upload the run to either youtube or twitch (yes you can upload stuff to twitch)
"TAS leaderboard" isnt really a good idea. TAS sing isnt necessarily about being faster than someones tas but rather about making the fastest TAS in general as a team or a solo project using the fastest strats. though if there somehow was a good way to have a link to a categorys TAS on the games page would be cool. maybe if there was a page for every game similiar to the guide/resources/news/forums but would list the fastest TASes for each category not sure
asks how to ask someone for something without asking????