Your action does look a bit high to me. But that's not the main problem. Most importantly: You need to relax and reposition your thumb. Put your hand flat and relaxed on top of a table or desk, with your palm facing down. Just relax for a minute and let all the tension go away. Then gently rotate your wrist so your hand is palm up. Everything is still open and relaxed. Nothing is curled, bent, or pinched. This is my recommended left hand technique.