As far as I understand, domain lock will pretend us from embedding the video we have embedded on our domain, could not be embedded elsewhere, right? But hey, to embed Youtube Videos with killerplayer, they need to be "not privat" on Youtube. This means, everybody could embed the same video in just the Youtube style. Or is there something I did not know, that Killerplayer could prevent Youtube videos to be embedded elsewhere?

And whats the sense of CNAME just for embedded videos? As far as I understand, is your domain only listed/visible inside the source code, ain't it?