A concurrent stream is a playback session running at the same time as another session under the relevant account or system's counting rules. It is different from the number of devices on which an app is installed. Services may count live viewing, recording or other activity differently, so the applicable limit needs to be stated for the actual plan.
A practical example
A household can install a player on two televisions but use only one at a time if its plan permits a single simultaneous stream. Starting a second session may affect access even though both devices were configured successfully and appear in the household's app list.
A common misunderstanding
Do not interpret multiple installations as permission for simultaneous viewing. Clarify how the actual account counts active playback and any recording or background sessions before changing device registrations.
Related terms
General operational definition; actual service terms remain separate. Editorial approach