Press to 2x, Lock Screen, and Cancel Seeking are features that give you more control over your YouTube watch experience on your mobile device.

Use Press to 2x to bump the playback speed to 2x while watching a video.

Lock Screen helps you avoid disruption while watching a video in the YouTube mobile app. Locking your screen prevents unintentional taps or swipes from interrupting playback.

While you’re seeking, Cancel Seeking allows you to cancel this action and return to where you’d left off watching the video.

Speed up or slow down YouTube videos: https://support.google.com/youtube/an...
Lock your screen in the YouTube app: https://support.google.com/youtube/an...
How to use the chapter & seeking features: https://support.google.com/youtube/an...