It's surge. It also, in all of those videos, was surging at "full" throttle. Upon further investigation I had adjusted the cable incorrectly and was only getting 75% throttle.
So instead of the 17.5 psi that I thought was full boost, on a 14psi wastegate spring, I now have 20.5 psi. So, I have no traction, I don't think I have surge now at WOT... but it came on quite strong and I wasn't really paying attention to the sounds of surge, if any.
It also surges really easily during shifts. The BOV appears to be a little tight. It takes quite a pressure difference to open it. I think I might try and remove a coil or two and see what happens.
So, it's down at the moment while I take apart the wastegate and see if it needs a rebuild, and for a 8psi spring regardless. I'm also adding a flex pipe to the secondaries after finally finding a properly sized high-pressure flex joint. And some heat shielding and other things while I am there. It might be a little louder when I'm done.