All kinds of videos:
Headcam & trail videos
Did I miss one? feel free to suggest more channels.
and of course you should follow all the bike and components channels
Technical stuff and list of standards, and differences between standards, and info about tools …….:
http://www.sheldonbrown.com Is you wonder about standards, or have seen something weird on an old bike you want to know about, or find the right tool for the job, or want to know more about bikes in general check this site out.