You only showed it cutting so that’s What I saw wrong with that video. Trouble shooting in aluminum is kinda pointless, Things need to be close to perfect to make it work.
With a long zaxis you can have ringing from acceleration and deceleration at too high of speeds. You say slow but please give a number, slow is subjective.
I honestly think the biggest problem is going to be your z axis length and the speeds you are moving at right now.