There are scores of science channels on YouTube and a fair number of geology-themed ones. Here's a sampling of geo channels with a fair amount of high quality content. Do you have any others you'd like to recommend?
Structural Geology
http://www.youtube.com/user/StrucGeology
Volcano Chaser
http://www.youtube.com/user/volcanochaser
British Geological Survey
http://www.youtube.com/user/bgschannel
U.S. Geological Survey
http://www.youtube.com/user/usgs
IRIS Education & Outreach
http://www.youtube.com/user/IRISEnO
Instituto Nazionale di Geofisica e Vulcanologia
http://www.youtube.com/user/INGVterremoti
Hawai'i Volcanoes National Park
http://www.youtube.com/user/hawaiivolcanoes