Sorry no. My main problem is with the E string (4 string only) which I suppose makes sense. It is bad enough listening to me without having to watch it but I certainly don't have that effortless natural sort of movement so evident in your Vids. I use 3 fingers to pluck quite quickly but to slap I really find difficult. I must have watched hundreds of slap videos explaining the technique and part of the thumb to use. Is it like balance on a bicycle when by practice it just clicks? Do you suddenly find the right force to slap and the right place on the thumb for you? Pete. PS. Many thanks for your reply
If you're having trouble with your thumb, maybe visualizing bouncing a ball (like a basketball player,) with a little bit of rotation in the wrist might help get you closer?
Best of luck, and never give up!