Huawei Mate 8 - Manual (Page 13)

Exciting new features
6
Screen recorder
Use the screen recorder feature to teach friends and family how to use phone features
or record video game footage.
Before making a screen recording, ensure your phone is unlocked.
Starting the recording
You can enable screen recorder using one of the following methods:
•
Knock the screen twice with two knuckles, and then choose a video format.