Only posting to try to learn something.
I've watched the video over and over looking for the things people have mentioned in comments.
I won't bother tagging people....
1st comment of note, was "Looks to have pitched up quite aggressively & dropped a wing"
Appears to me the aircraft has actually become airborne in the 3 point attitude, and then dropped the wing. I just can't see a pitch up, which would validate a stall spin.
2nd Comment " Looking at the video it looks like asymmetric flaps has been the issue here."
From the video, there is ZERO evidence to support this, other than the aircraft's behaviour once becoming airborne. Even the replica use the original split type flap which from the angles in the video makes then invisible, until the final few seconds when the aircraft comes to final rest, and no flaps are down. yes it may have been torn off.
On a positive, the pilot can come in here and tell us what happened. Kudo's to him, he realised it was going pear shaped and opted out.