Thanks. I just used the timewarp effect in after effects, but I did render a bunch of shots and selected the ones with the least weird artefacts. All those shots were recorded at 60fps originally which really helps to get it ultra slow.

Thanks. I didn't spend too long as you can see if you look closely. The background doesn't actually change in those shots so the masks can be quite vague.

Thanks, I was trying to create the tilt-shift effect but sadly it was done in post.