the copyright issue is a serious one and discussed at length here:
https://steemit.com/steemit/@ura-soul/sharing-copyrighted-video-material-on-dtube-coule-put-steemit-s-future-at-risk-and-devalue-steem-my-thoughts-having-worked-in
maybe consider putting a disclaimer for now "you agree to upload only original content".
indiependently to what anyones view is on copyright, we know the Feds ( FBI etc) take it extremely seriously and last thing we want is to attract their attention already and see them crack down on the site or its developers.