I know that often video doesn't "show" what is happening, but watching this a few times, while the technique is being done crisply and cleanly, I don't see uke being off-balance - either laterally weighted onto one foot or uprooted onto tiptoe - before Kanai Sensei moves under her arm.
I don't consider it safe for me as nage to proceed if my opening hasn't unbalanced uke.
I may be off-base here but that's my honest interpretation of what I'm seeing.