The whip thing he does at the start of the trick looks like sort of a follow/jade whip variation.
Start from a trapeze. Grab the loop with your throwhand so that you can flip the yoyo over onto the back string. Let the slack loop in your throwhand hang loose, and you will be in a mini-trapeze with a slack loop in your throwhand. Dismount the yoyo, but don’t let the string drop from your non-throwhand. Swing the yoyo around your throwhand wrist, and then whip the slack loop in your throwhand into the gap of the yoyo, just like jade whip or iron whip. He also whips the slack in a circle while the yoyo is swinging around his wrist, so it is a bit of a follow motion where the slack follows the yoyo around in a full circle before doing the whip.
That leaves you with a wrap of string around your throwhand wrist. From there, he lets that wrap slide down over his wrist and starts playing around with the slack, which is a bit more complicated to replicate. The whip on it’s own is pretty cool, though, and you can do some interesting stuff just sort of emulating his slack concepts even if you don’t copy them exactly.
Here’s the best I can do with the second half. It’s not 100% the same as what Keiran does, but I think it’s mostly right and gets the basic idea. I’m really bad at landing the slack pinwheel part, so I wasn’t able to get any really clear takes of what is going on at the end, but hopefully it helps.
I also included a simpler ending that skips the slack pinwheel.