Dupe content doesnt hurt the site but I would argue that it doesnt help?
Post limit, so I am answering here.
Thing is, Steemit is a bit pervasive. One you're hooked, even if you are first creating the video on YouTube, and then post it to Steemit, the consensus mechanisms and incentives would work on altering your behaviour that profits you, the content creator and the network as a whole. People here prefer to vote for things, that make everyone's situation better in that regard.
So, to be successful in monetizing their stuff, YouTubers would have to adapt. Adding a new revenue stream usually requires adapting to it.
Whats to stop me from putting up their stuff and monetizing it?(Besides ethics)