I lost the AT&T chat log that I saved from a session about 2 weeks ago. I started a chat because I had concerns that my data would be slowed at the 22gb mark since I live in congested Florida. I was in DC at the time for the 4th and was using my data pretty heavy along with my 10gb of included tethering to stream movies at the hotel on my Apple TV that I brought since the wifi was pretty bad. I was assured that my 22gb of data and 10gb of data were separate entities, and that each of my 3 lines were good for the 22/10.
In the end, the agent I was chatting with actually informed me that AT&T would NOT actually slow my data down at or after my allotted 22gb. I don't know what to think but I have to say after using about 25gb with 2 days to go in my billing cycle, I have not had any issues whatsoever streaming HD video through my MLB app or Netflix at any point in the day or night.