My DS loves Baby Signing Time! My son learned the sign for wind from the DVD. I did not go over the sign for wind but since it is easily recognized I realized what he was doing. Today it was windy out and our palm trees were making noise due to the wind. As we passed the tree it I realized why he was waving his hands in the air. It was cute to realized he taught me a sign.
Just thought I would share.
So cute! I just learned that sign too. :laugh: My son signs tree to me when the wind blows so I thought I would teach him how to actually sign wind. Congratulations. It is really exciting to see them learn!
I find your post interesting too because when my son was more of a baby I was really discouraged about the idea of showing him videos. I had read a few times that babies really need the human interaction to learn. Then I saw a video on youtube (which I cannot find now to save my life :mad: ) from a respected university that explained an experiment they conducted where they brought infants to their research center for 12 hours a week and spoke Mandarin to them. Another group of infants watched a video recording of these sessions.
According to the researcher, infants are born with the ability to hear all the sounds from all languages but somewhere around 8 months old infants loose the ability to detect sounds from languages foreign to them. After so many weeks they tested the babies and the babies from the group with live Mandarin spoken to them could detect Mandarin just like an infant with Mandarin speaking parents whereas the babies from the video group reacted as if they had never heard a word of Mandarin in their lives.
It was enough to convince me not to show my son videos in Spanish even though I really wanted him to learn. I can speak Spanish but English is so much more natural for me with my baby. Then, about a month ago I had some songs playing from videos on youtube and as clear as day I heard my son say “apple” which was the first time he had ever said apple. The song was saying “An apple is red.” Of course I have said apple to him before, but clearly whatever he saw/heard from the video cemented it for him enough that he could say it.
So, in your experience and in mine, they do learn from videos. I feel a little silly for this to be a revelation for me!!!
They do learn! Especially when a parent or a loving relative is watching, gesturing, or explaining to them. TV is not all bad, it’s just a matter of choosing the right materials and not using them as a stand-alone teaching substitute. We love Baby Signing Time too and all the Signing Time series! 
DD is still going over them especially that she can now sign accurately with her fingers. It’s a challenge for her and she makes sure she got the hand/finger placement right on the dot. It’s one of the few videos that she still watches (we started at around 4mos old).