Some questions about the music video for Born Slippy .NUXX

[Milking Your Plastic]

Being a fan sometimes means wanting to know the smallest things about your area of interest that others would think WTF or who cares. Right?
My first musical memory of Underworld was seeing Born Slippy .NUXX on an Australian music video show called "Rage" in 1996. So yeah, it holds a certain significance for me, mostly nostalgic.
Questions
Where was this video filmed?
I always thought it was a hospital or office. For a longtime I thought that Karl was kneeling down in a bathtub because of how the shape of the wall looks and you can see a tap near him, but his just kneeling on the ground.

Does anyone have any information about the hat his wearing?
I thought it was russian. But now I'm not so sure.

Does the floating square mean anything?

Who is the person smiling at the start of the video?

Please be polite. I don't want to read stuff like "Who cares" and "get a life". I hope UW fans here are genuine enough to avoid posting comments like this.

Thanks