I just started posting in DTube lately, don't really know much about how it was before. Was watching the new curation blog. According to steemreports, Dtube is voting more users lately which is great. As far as I know, DTube has been quite supportive and I think voting more, especially newer users, is certainly a good way to motivate more users, especially understand current econs on Steemit.
Content based contest is certainly a good idea since thinking of a new theme isn't so easy. But for myself, I feel really nervous for contests, so I don't normally take part in them lol.