I will point out a few errors I found in Mark's video when he does a little comparison against the R5...I think that is one part of video that he should have stayed away from as he has never shot an R5.
He says the scan speed is 15x the R5....that is incorrect...we assume the A1 is 1/240 (at least 1/200) and the R5 has been tested to be ~ 1/60. So we are more like a 4x increase. The R5 doesn't distort as bad as the golf swing image...that is more like an A7RIV at 1/15s. Also when he says the R5 has blackout that isn't really correct. At H+ in 12FPS MS or 20FPS ES the R5 does not have blackout. What Mark should say is the R5 does not have a live feed. The R5 is doing a slideshow but at 20FPS it is almost as good as the A9/A1 if you hold the shutter down...however if you go on and off the shutter you get the stutter as you drop out of slideshow mode and back into the live feed. That is the advantage of the A9/A1 over R5...not blackout.