This video has been around for a while; my now 14yr old daughter used to watch this video everyday from 9months old on. No kidding, by the time she was 18 months old, she could identify ALL the letters if you asked her to point to any one!
Now, I have a 4yr old, 3yr old, and twin 2yr olds who are really learning alot from this video, albeit not as fast as my 14yr did.
I would recommend this to anyone with kids from 6months up!