Heck I try to resist on commenting on other folks videos, it is too easy to arm chair quarterback them for sure. Reading through the comments though based on IS/IT skills and what constitutes IT and what is Jiu Jitsu I'd make this base comment.
It ain't even good Jiu Jitsu or Judo for that matter! There is a reason you don't practice this type of move that way in BJJ or Judo...people simply won't let you do it that way.
The way that guy leans in to split uke, I feel the uge to row backwards, yank him forward off his base and have my way with him...way too committed and no kuzushi what-so-ever....or kuzushi at the wrong time..if you ask me.
No, good kuzushi requires you to have uke press forward into you and you have to shift him up and load him by coming underneath him. If you move your feet or not is really immaterial at that point I think as the loading has to occur BEFORE you irimi or he simply is gonna by out of there. He will feel the proprioception of what you are doing and adjust.
So, I agree with George's assessment above. I can't tell you much about the difference between good IT skills and Jiu Jitsu...but I will tell you that it ain't in the irimi at that point in a non-compliant situation where uke is walking a fine line in Kaeshi-waza.
That said, I think there is a good version where you CAN irimi prior to actually making contact to nage, however, kuzushi is established with INTENT through atemi and uke adjust to avoid it so by the time he grabs he is grabbing to stablize a situation gone wrong for himself.
I am sure the video was slowed down in attempt to communicate some fundamentals, but I personally believe they left out some very important things concerning Ma ai and loading which are really the fundamentals of what I consider "good Jiu Jitsu"