Your technique and relaxation are pretty remarkable considering the years you train. It is also very rare at your age to see players like you focusing so much on the basics because they understand the importance. Most people get overexcited with equipment and forget that the player shines the paddle not vice versa
Now since the internet is a really tricky thing, my personal "suggestion/advice" is two things I learned from kreanga, although he wasnt even coaching me, we were just fooling around talking about TT
1st is : always aim a little higher than your current potential, that goes mainly for technique. Dont train too easy drills or too hard just to prove yourself or boost your ego, it is a waste of time and most of the time results in poor psychology/development and results.
A little higher means that ur difficulty level of drills must be the one that challenges your body and brain to adapt, but does not result in crappy technique/footwork/recovery etc.
To be more specific : if u cant handle the pace/speed on certain drills, lower the speed so that you can execute with perfect technique zillions of times dont try to fly before you can learn how to walk its pointless
So if u cant do it perfect a zillion times lower the difficulty as needed, if it is too easy or boring adapt again as needed.
2nd is recovery after stroke to ready balance/position for the next stroke which is a difficult skill to master even for the pros and its a common "mistake" among hobby/amateurs/beginners . When u feel ur technique is good then start focusing on recovery in your drills. Everybody can topspin hard, very few can do it ball after ball after ball after ball etc etc
So even for your videos, if you want to provide us something I think it would be 100 % efficient if u post a match against an equal level player (little better or little worse does not matter). Cause Im quite positive that you will get much better observations/suggestions that way. If u play a much worse player you will just look perfect and vice versa if u play against a much better opponent.
Of course one can say that even if u play a worse player some things are pretty obvious to improve but that is were 1st advice of kreanga comes to play
Good luck and be patient