Correct. If you want to watch TV at the same time from multiple devices, then you need a donation for each. If you only plan on watching TV on one device at a time then you can use the same MAC.
You are correct that what you said was correct, however the way you worded it, it made it sound like that this is the only MAC he could use and I do not see where you mentioned that he could generate his own MAC. Just trying to make sure that people are not getting confused.