Hermit crabs are interesting creatures. They all have a little mobile home, which is a shell strong enough to protect their soft abdomens and at the same time, snug enough to maintain a proper moisture level.
In the video, you can see a beach goer try to help a hermit crab to find a proper fit.
The hermit crab tries one, and then another, and another, until it finds one suitable. Well, if that is something this creature intends to stay for a long time, it has a right to be picky: just like us in finding a home.