YouTube Speed Changer by mikuloverboy

A Firefox WebExtension that allows you to control YouTube video playback speed with keyboard shortcuts. In addition to adjusting the playback speed, this add-on modifies YouTube's native time display to show effective times (i.e. the adjusted current time and total duration based on the playback speed). A small overlay in the top-left corner also shows the current playback speed.

Features

Playback Speed Control:
- Increase speed by 0.1 (press d)
- Decrease speed by 0.1 (press s)
- Reset speed to 1× (press r)
- Set speed to 2.5× (press g)

Native Time Display Modification:
- Shows effective current time as:
- Effective Current Time = current time / playback rate
- Shows effective total duration as:
- Effective Total Duration = total duration / playback rate

Speed Overlay:
- Displays the current playback speed (formatted to two decimals) in a semi-transparent overlay on the top-left of the video.

Smooth Updates:
- Uses a smoothing mechanism for updating the effective current time display to prevent flickering at high speeds.