Currently this kind of embedding (user interface) could cause some problems in some countries like Germany.

In Germany there is a law that when any contract of purchase is made on the web, the decisive button must conform to strict regulations. That is because in the past there where many frauds in Germany where contracts where made by clicking some buttons with and giving the address of the customers that lead to huge recurring costs -- and the customers believed that they just joined a user base without costs. To prevent such frauds, this law was given, but the regulations are rather strict. So the button must clearly tell, that a sale is to be made. I believe thus, a service like in the demo would be illegal in Germany.