On PBS, they have a show called "Signing Time" which is really great, and I've watched it with my kids. I prefer this better than the Baby Einstein series. AND, since the show is on PBS... all you have to do is record it, and then you don't have to buy it. You can just record as many as you want, and then you have a whole "library" of it on your TV. In our State, this show is usually on Saturdays. So just check to see when it is on in your city.
Here is a link for it:
And you can get many baby sign language materials here.
I taught both my kids sign language from when they were babies. Babies catch on fast. But I"ve found that just doing it with them, everyday, and at every moment you think about it, it really what works best. Because then, it is not just "passive" watching... it is doing it in conjunction WITH an action. This is how they learn and learn to correlate the "sign" to the object or activity.
The MAIN thing is, you have to do it consistently. Because babies and children learn by repetition.
In any activity you do, or book you read, you make the "sign" for the object or action. ie: For example: you are getting milk for your baby...so you SAY the word "milk" while simultaneously making the sign language for "milk" etc. Or, you are reading a book and pointing to a frog... so you SAY the word frog, while making the "sign" for it at the SAME time.
Or say your baby needs help with something...so you say "Help?" while at the same time making the "sign" for "help."
Same thing for "please..."
I have found, that it is also VERY useful to teach a baby/child "functional" words, instead of just nouns. ie: "help," "more," "please," "stop," "come," "finished," "eat," "hungry," "drink," "sleep", etc. This way, they can actually tell you what they NEED, versus just pointing to something. And, this aids in communication... and helps them to actually "tell" you what they want. My son used "functional" sign language words, more than he used nouns... and it really really helped, and lessened any frustration for both him and us as Parents.