The quality between the two formats is stunning... BPG version looks blurry compared to the mp4 version.
[1]: http://xooyoozoo.github.io/yolo-octo-bugfixes/#production&bp...
Separately, though, take a look at other features of the image: the beams running lengthwise down the shell, specifically the ones on the top left of the image. The BPG version makes them look niceeeeee and crisp, whereas the WebP version looks very bad.
Other places where I think the BPG compression looks noticeably better: her uniform (right sleeve, right leg, etc), the rivets along the top edge of the platform she's standing on, where she's grabbing that power tool.
One thing I noticed in the BPG version is that some gradient areas have more visual banding compared to the WebP version.