Greasy Fork is available in English.
Adds keyboard shortcuts for controlling HTML5 media player (audio/video) with OSD support. Seek media to 0%, 5%, 10%, ..., or 95%. Rewind and fast fordward media by 30 seconds, 1 minute, and 5 minutes. Change media speed even beyond YouTube's speed limit. Change audio volume to 20%, 40%, 60%, 80%, or 100%. Change video aspect ratio for TV and letterbox content (for widescreen monitors).
