SeikisoViewer is a browser extension for Chrome developed by なかむーら. It enhances the YouTubeLive experience by displaying comments on the video in a style similar to that of NicoNico Douga.

The main features of SeikisoViewer include the ability to display comments on the video screen with various customization options. Users can choose the position of the comment display (either at the top or bottom of the video), adjust the speed at which comments appear, and enable automatic transparency when there are many comments. Additionally, users can toggle the display of comment icons and names, and even change the position of the comment input field, allowing for transparent display on the video itself. This enables users to watch the video in fullscreen while simultaneously commenting.

SeikisoViewer also includes a time memo feature, allowing users to bookmark specific moments in the video by clicking on the memo icon. This makes it easy to jump to those moments in the archived video with just a single click.

Please note that if comments are not flowing smoothly, disabling ad-blocking extensions may improve the performance of SeikisoViewer.