An old YouTube workaround for HTML video without Flash
A preserved browser-console workaround for YouTube playback in 2013, using a watch_popup URL before HTML video became the normal path.
Launch console, with shift+ctrl+i and copy and paste in:
document.location.pathname = '/watch_popup';
Now HTML video playback should work, without Flash.
You can also make a Javascript bookmark: http://s.natalian.org/2013-12-16/bookmark.png
Credit: https://twitter.com/rouadec/status/385068793673707520