Hi kla4
I’ve taken the time of actually explaining it to you in my post, but clearly you haven’t even read what I’ve said.
I cannot make it any more obvious.
1: I recorded the song track by track prior to recording the video.
2: Then during the video I play back my multi track recording and I play over it with one more track Live.
This is how every workstation user in the world make music.
Regards
James.