For what it's worth, the authors are both language experts with PHD's. I find it interesting that they say that children older than 2 or 3 can learn from DVDs. I am not certain they are right. I think that if parents participate in the viewing of the dvds and they interact with the child, then it is a much more interactive experience. We are using Speekee right now and I keep pausing it and have the children repeat stuff and they like it. My daughter is trying to sing the songs throughout the day on her own.
I am married to a Spanish speaker and I have watched Spanish TV with him for years and I did not learn to speak from watching TV. I imagine that if that same time was spent interacting with someone who could communicate back I would be much better off.