Interesting concept your post made me think of. If someone wants to better monetize DTube, DTube could maybe launch its own token as a STEEM community token. DTube could have its own token which would pay alongside of STEEM payouts when someone upvotes.

Then if DTube did advertiser integration, and they pay with the DTube token, could create value and solve this issue of 7 days limitation. DTube token could be an on-going payout past the 7 days for the likes, plus could also be a vehicle for ad revenue to give it value.

It's a neat idea at least.