Yeah, the video is decoded in js and converted to frames every time. First I tried making a <video> element and synchronizing it with page scrolling. But chang

Yeah, the video is decoded in js and converted to frames every time. First I tried making a <video> element and synchronizing it with page scrolling. But changing video time is asynchronous, so the relative positions of video and html content got wobbly. The only way to achieve perfect sync and "glue" the content to the background is to draw frames manually on scroll. And also round off the scrollY of the html content to the position of the nearest frame, so that there's no subpixel wobble either.