This is a really nice idea, at least "on paper."
I think that for this to work, at least in terms of bringing in people who can add lasting value to the community, we need to come up with a primary "pitch" OTHER THAN 'we have free money for posting.'
The rewards thing is like offering "free stuff" when you open a store... you certainly "attract a crowd" in a hurry, but that that crowd is made up almost exclusively of people looking for free stuff, not people who will become lasting customers of your business.
So, what do we offer "OF VALUE" to people that sets us aside? Well, no YouTube, Facebook, twitter bans for "saying the wrong thing" or supporting the "wrong" political party. We are also a one-stop-shop in the sense that one account can access video, gaming, blogging, crowdfunding, photosharing and more... across platforms with unique identities, but sharing a common core. You don't need 5 accounts here.
What else?
Great points @reddragonfly. I think one of the best benefits is finding an audience for their work. We are a pretty tight knit crew around here and by joining Steem, they will be finding community and getting access to an entire network of people that they never would have found otherwise.
Ultimately though, I think it depends on what the person is looking for. If they have previously been censored by YT or Facebook - then that talking point will be hella important to them. To someone who just wants to share their music and can't seem to get anywhere on Youtube - finding out about the Open Mic community and learning they can post their videos on Dtube as well may be a more captivating angle to discuss with them.