Google is your friend. Don't feel guilty about taking advantage of him occasionally.
I've never touched, or even seen, Chromium personally, but a few seconds of searching shows several add-ons available for Chrome
. (Chrome add-ons do work in Chromium too, don't they?)
Or if you don't want to go that route, there are a load of websites
that can grab videos from youtube and other sites for you. So you can use any browser you want.