I have to chime in here. The videos and any video aimed towards infants and toddlers are fine if it's in moderation. When Julie Clark, the founder of the Baby Einstein video first produced it, she explained that parents should participate with their children. She would show it at the end using a mom and her child as an example. She encouraged parents to talk to their children as the videos were playing. Combined with hearing their mother's words, the music and the visual, it piques children's interest. Why? Because it is active. You, the parent, and the child are both actively engaged. Learning is so emotionally based and children are so emotionally attached to their primary caregiver. You can do the same with bringing toys to your child or the actual object. The video was just another way to do it.
Once Disney bought out the Einstein company, you no longer heard Julie's suggestion to parents. Now hopefully most parents would never use this as just another babysitter, but I seriously think this is what happens.
I work with children from birth to 5 through Early Intervention. Many of my clients are children with Autism or on the PDD spectrum. I work in the field of special education. Parents have even said to me, "I put on the Baby Einstein videos, but so and so doesn't talk." I later found out that it is the baby sitter. Again, once and a while maybe, but some do it every day. Now, the Baby Einstein's videos do not cause Autism, but it certainly doesn't help to build language when used this way for any child.
BTW - I am a firm believer in no tv until the child has turned one. At two yrs., no more than one hour on an every now and then basis. From three on, no more than one hour a day. DS6 is now allowed to watch more than one hour of tv each day, but after dinner. It's hard especially on rainy or snowy days. The only exception is when they are sick, they get to watch more, and on family tv/movie night when we watch a movie together.