In the part where it says "Spot the difference" and everyone says "The BPG one looks worse". That's because BPG, even in "lossless" mode... is lossy. So you're

In the part where it says "Spot the difference" and everyone says "The BPG one looks worse". That's because BPG, even in "lossless" mode... is lossy. So you're taking a video with H.264 compression artifacts and recompressing it with HEVC artifacts. The quality can only go down. FLIF on the other hand is lossless, so the image would be truly identical (pixel for pixel). However the filesize will likely be much larger, as MP4 is a very good at lossy compression. What BPG is doing is better performed by HTML5 video formats that already exist due to hardware acceleration support for H.264 and better memory management for video. Also there are patent issues with BPG due to it being based on HEVC. FLIF is patent free, making it the more likely candidate for mass adoption. It's animation, like APNG is lossless and supports full 24-bit transparency (versus GIF's 8-bit). However the filesize for FLIF is considerably smaller than APNG, even when crushing it with algorithms like Zopfli. Still though, for full frame video, you'll have a better time with MP4, though FLIF will be better quality, it will only be marginal and not likely noticeable in most cases. What is interesting is the responsive aspect of FLIF. If you encoded an HD video, but only display it on a page at a lower resolution, it will only download the minimum amount of data required to display the image up to that resolution. So it could technically require a lot less bandwidth from a server compared to MP4 if the user doesn't fullscreen the video. But this is more to do with implementation than with formats. YouTube does this same idea, though with a completely different style of execution, in which they only give the the quality for the resolution you are playing it at.