Yes, you can post old videos on Dlive, as well as any new materiel, and you can even livestream from their platform. What's the benefit? Dlive has a massive amount of steem power, so they have a very powerful upvote to those who load on their site. Dlive doesn't take 25% of your earnings like Dtube does. They store your videos forever, unlike Dtube who will only store your videos for a long period of time if they make a lot of money.