yup.. the ultimate time slip.. digitally recorded ... and played back.
content on the DVR isn't "finalized" like DVD or Bluray media .. while it does have a start / end .. the rest of the media is stored just like it was when it came in the first time. So even though you're playing something that was recorded 5 weeks ago, the output and the parts of the DVR that are handling playback are still the same as before.
thus the problem is somewhere in the buffer handling, the pointer management, major or minor time index points, etc.. that it can happen from recorded material would lead to suggest that its not the OTA tuner causing a muffle, or if it is, its doing it in some way to effect the show during replay ... also you would hope that these things happen at different times from one dvr to the next .. else again something in the signal is being recorded and causing it ..
It would take knowing how the stream is sent, are there any special timer/markers in the data stream to help align all dvrs all players, etc.. but this digresses from the simple fact it does happen, we've all seen it, those that haven't should hopefully have given room to the possibility that it does and has happened, rather than "doesn't ever happen, you're lying" kind of mentality.
I'm also one that's had it happen to HD content .... I can't really say its more to HD or SD content, because most of what I watch *is* HD. Rarely am I watching a non-hd station even in the premiums, I tend not to watch anything SD.
personal note and seriously an LOL moment for me.. I just looked at the guide to see some of the non-hd stuff.. and what do I find on EncrW/#341 ... Ronin in SD of which the first time I really had this annoyance (as above) it was during ronin..