I didn't read the entire posts but looked at your videos out of curiosity. I took many years off of playing tennis; I'd guess up to 10. Then I started playing infrequently and now more frequently the last few years. I'm amazed at the number of things I've learned in my maturity.
1) I'm better mentally most of the time.
2) I realize that fundamental strokes are much more important than just repetitive strokes.
3) I'm still remembering little things here and there that I'd forgotten.
Just the other day I realized I used to be a toe dragger on my serves. I think I must've stopped years ago due to the fact I couldn't afford shoes like I can now. The last two times out, I've begun toe dragging again and I'm amazed at the consistency I'm getting. My serve has been holding me back and has been very frustrating because it used to be the best part of my game 20+ years ago. It wasn't like it was a monster or it kicked up greatly or anything like that. It was placed where I wanted it and I could serve and volley behind it. Now, it's been just YUCK. However, I feel it is getting better and now I just need to continue to practice and work on my volleys (I still haven't figured out what the hack is going on here. I used to be very comfortable at the net!).
Good luck! I understand the fun, excitement, and frustration of starting over and rediscovering.
Back to using POGs. Why did I ever leave you dear friend?