The "YouTube Repeat Button" extension addresses the missing repeat button on the HTML5 YouTube player. By installing this extension, you can have the missing repeat button available. By default, the button is inactive. To repeat a single track, click the button once. When the extension is active, the button's color turns white. In this mode, once the video finishes, the extension pauses the player for one second, seeks the start of the track, and replays it. Please note that before the 0.2.1 release, this extension only functions in normal playing mode. If a track is in playlist mode and the repeat button is pressed, the extension will suggest switching to the normal playing mode. Furthermore, the extension is disabled when a new player is opened. If you wish to enable the button, append "&repeat=true" to the URL of the YouTube page. Starting from the 0.2.1 release, the extension utilizes the native loop function and maintains the loop state during navigation between tracks.