I'd follow up Lefty and Joans videos with Doug Swishers The essence of fly casting. The first two should get you on your way and Doug's has quite a few different easy to learn types of casts that will help you a lot on the stream.
(ps. if you buy the video you should also buy Joans book it helped me a lot. )

I have been trying for almost a year now to beg borrow buy or steal a copy of Tom Whites video on roll casting . Sadly I have been unable to find one.

Best of all was standing in front of Ladyfisher and Castwell at the fish-in so they could observe and then point out what I was doing wrong and how to correct it. That was the best help of all.

Ps. Castwell's pointers in his link were my starting point and really do work.

Another good tip from Castwell that really helped me is to close your eyes and cast, It improves your timing and lets you feel the rod loading and unloading.

and of course as always . Keep thy back cast uppeth.

When I first saw the Royal Wulff's Fly-O I thought it was probably a useless gimmick but last winter My local flyshop guy recommended I try it. I bought one and I really believe it was the single thing that helped me the most. Once you can lay the entire line out on the floor or the lawn you can cast a real #5wt line at least 60feet. I wore out 6 sets of yarn casting it in my living room but heck you can buy a 300 foot ball of replacement yarn for 4 bux. The link below will show you a picture of the Fly-O.

http://www.royalwulff.com/educational.html#fly-o