yes, it seems to be related to the season/episode data that was added to the EPG entries in the last 2 months.
Based upon what I've witnessed:
If the multiple records of a particular series have season/episode data and you don't play the most recent episode available, the autoplay will move on to the next episode after a 5 sec countdown timer.
If you play the most recent episode, the playing will stop after that episode ends.
If there is no season/episode data, the playing will stop after that episode ends.
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I'm still trying to figure out some stupid things that have happened. I've had the next episode play after the 5 sec countdown timer even after I selected cancel to end the timer and not play back the next episode.
I've also had an incident where I watched the most recent episode available and when that was done, the HR-34 streamed and played back the episode before that (for example, if the most recent episode is episode 10 of the current season, when 10 was done, episode 9 would start streaming and playing).
I wish DIRECTV would put a toggle in the settings to turn that auto playback off. It's annoying, especially if I fall asleep while an episode in a group is playing (or intentionally fall asleep to something boring for which I recorded 2-3 of them).