It seems pretty obvious this will work just as seen on the video. It shouldn't take too much practice or skill neither, and you should encounter no problems at all. Well except one. There's a probable chance one or both of your doves will end up dead when you pull them out of these small - too narrow - unpadded wooden cabines.
Not only are you supposed to stick you LIVING doves in those cabins, but also there's no way of performing this illusion without holding the box standing, which means one bird will be on it's back (don't they love that ?) and the other will be pressed with it's face against the narrow end of it's cabine.
I don't have the nerve to ever try and pull this off in front of a crowd (hoping the birds don't die), but more than that - I could never do that to a living creature.

I would have returned the item for a store credit, hadn't the shipping been so costly, if I wasn't worried this would end up with someone who would actually use it. It doesn't fit in the junk drawer, so it goes in the trash.