Here are two decent beginner's videos I came across today.
The first one is about dismounts and remounts. Great soundtrack, but I disagree with stepping through with the right foot on dismounts. Hardly any of the top pros step through before dismounting, because it's no faster than not stepping through.
I think the section on corning is pretty spot-on. But don't get too caught up in playing games in corners, the race is long and things get sorted out over time.
Here is a video of Tim Johnson doing a barrier set. He only needs to take two steps before the first barrier, because when he's dismounting he's already got his right hand on the top tube. More than two steps would be wasted time and energy.