One more Q Scrap - I feel stupid for not noticing the 2nd lateral movement vid before - I'm not sure how I missed it!

I was just wondering what the purpose of the band on the rear foot is in this vid?

Is it to speed up the pivot of the rear foot? I was just thinking that if I have a tendency to leave my rear foot behind too much maybe this is not something I should do yet because it might train my rear foot to stay back more - resist the band?

Is that right or would it help train the foot to stay foreward? Do people often leave the rear foot behind because it's slow so speeding it up will help to eliminate the problem?

Or does it train you to keep your back foot under you because too far foreward or back and the band will pull you off balance more easily?

Sorry for all the Qs - I find these things difficult to conceptualize sometimes!