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.
I don't know if I understand you right (my English is not perfect), but when you mean, that using Bitcoin could prevent this from being illegal: I don't think so. The problem is not the amount of payment or the type of payment, but that it is a sales contract (at least in Germany, every sale would be made via a contract, if explicitly written or not -- also a handshake could be seen as contract). And the law just says, how any sale contract must be made ... There must be a good visible button that clearly states the intention: "Buy with costs" or something similar. The customer must be very clearly informed about the sale and the fact that he is making a sale now. Your demo informs afterwards in a rather weird way. Just giving a link and say "read further" or similar would be accounted to be a fraud, I guess. I am also not sure that having a different text would be enough.
I am no lawyer, but one remedy could be to have some kind of "frame contract" where you buy an amount of readings in advance -- and the readings afterwards could be accounted for with such a system. But such a frame contract would of course counter your ease of use goal -- and of course would bind the customers what would counter your goal to lower barriers.
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.