Do we have to bet the 100 bucks we deposit during the playoffs?
there is no specific rule about what you have to bet on, if you want to use the 100$ to bet on something else like NHL playoffs, tennis, casino or something else, that is fine.
despite the fact that there is no written rule, I would hope that those who deposit do play.... As you know, this contest is designed to attract players to Bookmaker, not those who simply want to take advantage of the contest but have no other interest in Bookmaker.