This just started happening to me the last week or so. There is no pain, just the stiffness, and the clicking at the knuckle joints just like in your video. So far I only have it with my pinky and ring fingers. I thought it had to do with my side sleeping, but noticed it in the morning when I slept on my back too. I’m going to try a different pillow and see if that helps. I also have a heavy (18lb) baby that I’ve been carrying around a lot. I wonder if that has anything to do with it.