Make the video progress bar at the bottom bigger (thicker).
I watch a lot of YouTube, and at the bottom of each video is what I call the "progress bar" (there's a formal word for it, fuck if I know what it is - I don't get involved with video), and I will hover my mouse over it, to "scroll" through a video to get to a particular part when the uploader doesn't have the courtesy to timestamp their content. When scrolling, my mouse always goes either just OVER or UNDER this "progress bar" feature. I'm so so so carefully moving my mouse from left to right, and then the cursor moves ever so slightly UP or DOWN, and I lose where I was. Of course, I just reposition the cursor to where I was, but I ALWAYS fall off that fucking thin line.
Just make it a few pixels THICKER, so I don't continually lose my spot. The thing disappears when my mouse isn't over it, anyway, so it isn't "blocking" any content when I don't need it. Just make this feature an easier feature to use!