(Not recommended for mobile browsers. Videos not playing in Firefox?)
This is usually an issue with a plugin or browser setting. I had to use Refresh Firefox to fix it on my side, but this removes all plugins. Use at your own risk.
These timings are approximate based on indicator opacity. This tool has not been tested with frame advancing.
Press any key during the animation to practice the timing (unfocus the video player controls first).
(Note: These windows are very small, and responsiveness between your keyboard and the browser can vary. For accurate results, practice on your console.)