I think that the reason they are doing it is to drive traffic and publicity to their cause. In the video they mention again and again how many twitter followers they have etc.
Look, I don't want to be too critical. This is fantastic and kudos to them for doing a great job. It is just this one thing that seems silly other than that it sounds fantastic.
Regarding driving traffic - sure, there is at least a minor "viral" impact from the system. Keep in mind, MassChallenge is a community. Driving traffic to our website helps the whole community, i.e. there are spillover benefits for other startups when one startup convinces their supporters to visit and browse the site. There's no profit at the center of the system -- so this isn't a selfish motive -- it's designed to benefit everyone.
We are still a relatively young startup ourselves and continue to refine our approach ... so there is definitely room for improvement in areas. On balance, though, we are confident that our processes work. We'll continue to refine and definitely appreciate the feedback.