I cannot tell from the video noise.
I am with Blaner, slide the jug off and have a look if in doubt.
Sooo easy with an aircooled motor.
Compression has very little to do with piston slap, not a valid test for it, but if compression is low, good reason for new piston and rings.
While you have the jug off (don't need to touch the head) measure your piston as well as the clearance.
Put on a new base gasket and you can keep riding your quad while waiting for your parts to come in.
I am quite familiar with piston slap and what can happen.
Blaster pistons are weak because of the large window in them.
When the window breaks off the crank will push the piece through the case at the bottom or into the gearbox.
The broken piston below resulted in a 1" square hole in the bottom of the case.
Another engine we took apart was running fine with only a bit of slap had 2 edges of the piston window cracked.