It should just slide off.

If you aren't able to get it off, you can always unscrew the boot and large silver plastic ring off from the trim. There are 3 screws holding it in, you can see them in your image above.

Might give you some more room to work with. Not 100% sure if it will help with your install though, as I'm not sure how much room you need to access those bushes.

The boot can also be detached from the large silver ring. There are rubber tabs that pull through the large silver ring. See attached image. You can ease them out backwards with a small flat screw driver.

The smaller silver ring also detaches from the boot. It unclips from the rubber. Be careful not to break the tabs when removing it!!! Again, see the attached image, the small black part sits on the inside/underside of the boot and clips into the small silver ring on top.



Only thing I can think of, of why it might be stuck. The rubber might be pinched against the shaft causing it to be stuck. But from looking at my boot and the black clip, there seems to be plenty of clearance around it.

I'd try easing it up with a bit more force? Failing that, I'm stumped as to why it may be stuck. Previous owner glue it in place? But it doesn't look like it from your video, as it does move up and down.