Scrolling through that landing page felt a lot smoother & snappier than I would've expected for a page looking like that.
It's clever, but honestly I don't care how smooth it is. Scrolling should simply scroll a view up or down a page. Not invoke animation. We already have established UX patterns for playing media, slowing it down, speeding it up, randomly seeking through it.
JS animations obviously don't take the place of video/audio media that you'd play/scrub through.