Yea I've noticed that too, First one for me was actually in that song I linked to Kag the punk one. First word was "Saramdul" I'm like I know that!
It's great, definitely the easiest and fastest way I've come across of learning another language, but less comprehensive I think than a book series would be because if you read the books you get cultural notes on usage and things like that so that's why I bought the book too and am watching TTMIK to help bridge the gaps Rosetta Stone can't cross but for learning the language in general I think it's the best.