As part of a video project for Midwest Permaculture, I've put a lot of work trying to survey all of the videos on sustainable topics that exist on the internet. The results of my efforts can be found on my YouTube profile. It's a library of over a thousand videos, with topics such as cooking, permaculture, permascience, deep green, gardening, strawbaling, building green, sustainability, sandgardening, solar paneling, reciprocal roof construction, the end of cheap oil, farming with Far Fewer Fossil Fuels, etc., etc., etc. You get the idea -- a video for every topic! The majority of videos are ten minutes or less, and it's a great way to quickly educate yourself on a variety of topics.
There are a lot of videos to wade through, so to get you started here are some of my favorites:
Peak Moment
Ryan is Hungry
Eat the Weeds
Garden Girl
Talking Stick TV
Andrew Faust
The Real News
Milkwood Permaculture
Cooking Up a Story
Permaculture Science
Alex Munslow
I would be remiss if I didn't also post the fruits of my labor, which can be found on Midwest Permaculture's YouTube video page.
I'm also interested in adding to this list. If you know of a video that's not here and should be let me know.