what trick is this ??

Yo-Yo Tricks
1

anyone know what this trick is called at 0:55 ??

2

the trick and the 55 second mark is called a gyroscopic flop here is the tut:
http://yoyoexpert.com/learn/067-expert-gyroscopic-flop.html

3

GYROSCOPIC FLOP in expert section

4

That’s what Hardcore_Max said. Please don’t just repeat what people say. It’s not very helpful.