Youtube Keyboard Shortcuts: like/dislike, backup/restore position, change speed, picture-in-picture

This script adds keyboard shortcuts to perform common actions on YouTube without clicking or exiting a full-screen video.

Shortcuts

• [ to like a video
• ] to dislike a video
• B to save the current playback time, meaning the script will remember your current position in the video
• R to restore the saved playback time, jumping back to the moment when you pressed B
• H to enable or disable Picture-in-picture mode, creating a floating video that keeps playing even if you switch to another application
• } (Same as Shift + ]) to increase playback speed by 5% (so going from 1x to 1.05x to 1.1x… etc as you press multiple times)
• { (Same as Shift + [) to decrease playback speed by 5%

Other features

• Discreet notifications are displayed when you use these shortcuts, so you can tell what happened even if you're watching in full screen.
• Notifications can be disabled by changing a single line featured prominently at the top of the code.
• How long notifications stay up (2 seconds by default) can be changed in the code, it's easy to find.
• The script tries to remove the built-in notification that says "Feedback shared with the creator", although your can disable this.
• The speed change for { and } can be configured in the code as well; it's 5% by default but the constant can be updated in a single place.