AT&T Unlimited Data vs wifi hotspot usage

It looks like whatever connection was used to initiate the streaming service is what stays with that content. Since the phone probably connects via the data plan, it would be data. I don't think you can connect the phone to your own phone hotspot; only make it a hotspot for other devices. But it looks like you can only stream from one or the other, not both without a serious reduction in speed. So even if you have all your phone data and hotspot data available, they will throttle your simultaneous streaming over both down to a low amount that could cause one or both to continually buffer.