Hey Casper, sorry on the slow reply we’ve been away at the US Smash and I missed this. So I think using more legs and waist will help a lot rather than using your arm and shoulder like you said but it does take time to get used to this and do it all the time I think the main things to work on now are the recovery between shots, keeping your bat high like you said will help this a lot. Also staying relaxed and trying to always be on your toes will help the recovery too.
A lot of the time just being under control and not rushing will help players as well, this isn’t easy but for you I think is a good thing to focus on, always trying to stay smooth and relaxed in your shots and take your time. You were doing some nice attacks after your serves so definitely keep that up. Lastly it looks to me you play much better when you focus on spinning the ball well and not going for too much speed to earlyso keeep this focus on all your shots as well! Dan 🙂