Videos are good as they show good habits and, if you're lucky, are well-worded. The difficulty lies in translating the process from visual (watching the video) to kinaesthetic (actually performing the casting motion).
The most important part of the video is the guy beside the caster. No number of great videos can replace a teacher at your side while the fly rod is in your hand. Video taping yourself casting can help you correct mistakes as well.
Also, start with short casts with lots of room around you, either on still water or a large patch of lawn such as a school field. Clip the bend off a wrecked fly you no longer use and tie it on the end. That keeps things safe and helps your cast to naturally unfurl.
And, most importantly, have patience with yourself. Good luck!