The contest that you are hosting is a great thing.Although the profit that you are making is a concern.
To make it more successful You can donate Steem in place of DVD and ask all the winners to powerup with their winning prize.This the value of invites of the participants will increase and ultimately your profit will also increase.
You can also ask some witnesses to donate to this competition and you can may be so free promotions for them. Anyway if these ideas bring fruit or not yours is one of the best contest hosted on steem.Keepon doing it.
@bunnypuncher.