A D.Tube playlist functionality would be very good since you also can't create multiple channels (excepting you've got multiple phone numbers available). If I create content of different types, so for example programming tutorials and comedy videos, I want to seperate the videos. The possibility of creating playlists would be the least thing that would be necessary to do that.
Just btw, something I noticed: The quality of the 480p videos is much, much better than on the most other platforms, because they use a higher quality setting. D.Tube showed me that 480p is still viewable and not as bad as you might think. I like it :)