This is torture, this video is being flagged all over the World, because what you see is not a relaxed bunny, but a terrified one! First, bath for a bunny is very very dangerous for his healt. Second, when bunnies are put in that position with the belly upside, they immediately frozen and stand still, because it's a terrified reaction to a predator attack: they pretend to be dead! So it's not relaxed, actually he is terrified! Please remove the video, it's very contributing to bad education about how to manage a bunny.
P.S.: I know it could sound absurd if you don't have experience with bunnies managment, but it's simple: if yuo don't trust me, just take your time to check, do some research on internet about the video itself and about bunny healt. Thanks.