Synchronized Playback for YouTube Archived Live Streams

An extension that synchronizes playback of YouTube livestream archives.

This tool synchronizes the playback positions of multiple archived YouTube Live videos. It is designed for archived streams, enabling simultaneous viewing of multiple perspectives—such as collaboration streams where several creators broadcast the same event from their individual viewpoints. When watching these archived streams in separate windows, playback positions can be automatically aligned. Press the [SYNC] button to enable synchronization. - Gray [SYNC] button: Not synchronized - Green [SYNC] button: Synchronized - Red [BASE] button: Set as the synchronization base The playback position of videos with a green [SYNC] button will align with the playback position of the video marked with the red [BASE] button. Synchronization is calculated based on the actual broadcast time during the live stream (stream start time + timestamp). * Edited archives are not supported, as accurate playback position calculation is not possible. While synchronized, play, pause, playback speed changes, and seek bar operations are immediately reflected in all synchronized videos. All control operations should be performed on the video marked with the red [BASE] button (the synchronization reference).