That is no longer the case. Part of the TimedMediaHandler rollout last
year was the added functionality to generate derivatives in multiple
resolutions. This gives you a YouTube-style selector when viewing the
video which allows you to pick the resolution you'd like to play it
in. Moreover, when embedding a video in a tiny pixel size, the player
will "pop out" when clicking the video to enable you to actually watch
it.

https://blog.wikimedia.org/2012/11/08/introducing-wikipedias-new-html5-video-player/