javascript:(function(){var video=document.querySelector("video");if(video){var speed=prompt("Enter playback speed (e.g., 1.5, 2, 2.5):", video.playbackRate);if(speed){video.playbackRate=parseFloat(speed);}}else{alert("No video found on this page.");}})();
or
video.playbackRate = 2
:screenshort --fullpage