Walkthroughs for custom maps.

I believe that anyone can choose any available nickname they like.
As for the SHA and its capabilities, this item is practically unusable for offline tournaments. By the way, the item has been fixed.
Regarding the speedrun on Metatasker, it's a comparison within certain limitations of the SHA, used by Rouzkavalier. And this is not an official competition, so there is a certain possibility to violate these conditions; much of it, as in online play, is based on trust.