Earlier quoted context omitted.
Unless somebody's producing ads, why would he insist on having the video "inline like on the desktop" on the small screen of the mobile phone?
To replace GIFs. I don't have a problem with users being able to opt out, etc. But GIF's are still useful, yet a huge drain on resources. If for nothing, I want my cat videos still available inline without having to click them.
Hardware video decoders mostly only handle one video at a time and if you could multiplex the one decoder the chip has, to keep up with multiple videos playing at once it just might take a milliwatt or two.