How can I convert a video to BPG format? BPG= Better portable graphics
It looks like BPG is at quite an early stage of development.

To use it, you would need to install an encoder, to convert your video to the BPG format.  At the moment, all of these encoders are command-line only.  You can find links to the encoders on the official site.

Note that the format doesn't include audio currently, so it may only be useful in some circumstances.

You might be better using a more conventional video format (h264, mp4, webm), but concentrating on encoding it with the most appropriate bandwidth and quality settings for your needs.