That's a fun video. Thanks!

I've seen the fabric metaphor before, but I'm still having difficulty on not separating time and space from each other. I think now I'm very close to understanding though.

I'm starting to think that space is not really a volume, and it's more of a relative thing. Like if right now we could get rid of the half of the matter in space, like draw a line and cut it into two pieces like a pie, and simple erase one side, then the new center of the space would be the center of mass of the remaining half. Or let's say, if there was only one particle in the whole universe, then there would be no space since it couldn't move relative to anything. It couldn't have speed. So, space is not actually an empty volume, if there aren't more particles that can move relative to each other. What do you think? It's not correct, right? Is it?