article author here.
odd choice indeed, I wasn’t thinking clearly when I experimented and wrote the article.
putting a black and transparent image atop the video sounds like a much better idea — i will try it and see if it works. thanks for the suggestion!
Not sure why they've done this, perhaps something about the HDR approach requires both the black and white to be a part of the same video render.
Also - I'm not sure if it's a browser default or some other website CSS but imo there's no real reason long press shouldn't work on a video anyway... videos need accessibility too.