HTML5 Syncer is a free Chrome add-on developed by crabshank. It falls under the category of Browsers and is specifically categorized as an Add-ons & Tools program.

This add-on allows users to synchronize two HTML5 video and audio streams, even if they are playing on different tabs. By simply clicking the popup, users can scan each page and press the "Sync" button to generate sync buttons next to the video or audio. Users can then click these buttons, preferably when both streams are paused at the right times, to synchronize them. Additionally, users can press the "Flush" button to remove synchronization.

HTML5 Syncer ensures that the synchronized streams pause, play, change playback rate, and seek together. Users can also check the Developer tools console for additional information.

Please note that if the delay does not show up on the green sync button, users may have to go to "chrome://extensions/" and click the reload icon for this extension.

Recent updates have included faster code for finding streams, improved element handling, better handling of streams waiting for data, and fixes for various issues.