I play youtube videos in VLC. No JS required, and I get higher quality sound as well.
Depends how you're counting. Using that 100kb of code "as intended" essentially requires Firefox (95MB) or Chrome (153MB), or some proprietary alternative.
To use VLC instead, we can get by with something like dillo (1MB) and youtube-dl (1MB), which (added to your 30MB estimate for VLC) is much less client-side code.
(Size estimates taken from packages.debian.org)
Because then you have the 7GB OS + 95MB Firefox + 100kB YouTube vs. the 7GB OS + 30MB VLC + 2MB youtube-dl
And, additionally, the browser is just a document displayer, like a PDF viewer, or an image viewer. 135MB for that is far too much in any case.