I got no extension

I‘m still struggling hard with extending (mostly on the downswing). My finish looks like Walter Hagen’s (if you’ve ever seen his swing) who Bobby Jones once supposedly said “He swings like a wounded duck.” My biggest issue is when I do manage to extend on the downswing my head ends up about a foot in front where the ball position was. I keep going back to this, but I feel like I’m missing something. https://m.youtube.com/watch?v=1aWTy3qjB_I