Here's what pietro has posted about the "Maybes", and the Redeem feature.
"There's a new feature we call "REDEEM". The basic idea is this: whenever you annotate one of the "maybes", instead of giving you a small number of points for your good faith effort, we will instead hold off on giving you any points until we can turn the "maybe" into a "yes" or a "no". Once we accumulate enough answers from other people to come up with an expert-like "crowd answer", if your answer agrees with the crowd answer you will get as many points as if it had been a calibration movie! But if your answer doesn't agree, you will get no points. Whenever one or more of the vessel movies you have answered is assigned a crowd answer, you will be notified, at which time you can click to redeem all your points.
Please keep in mind that when we first roll this out, it may take a while for your maybe answers to reach maturity. But once they do, you will start to see big points rolling in for all of your correct maybes. Indeed, some days you may log in and get more points by redeeming your correct "maybes" than by annotating new vessels."