The most frustrating thing about this is that the whole episode recorded perfectly well, and I even saw the video file sitting where it always does as an M2TS file, which Roxio uses for the conversion and then deletes. I suspect that the Roxio software wasn't written to expect file write errors and even though the newly encoded MP4 didn't get saved to the hard drive it went ahead and deleted the source file anyway!
Oh well, I recorded another episode which was much shorter and finished off the series. I've been thinking of a few ideas of what I'm going to do next, one of which is something not related to videos so I'll talk more about that when I have more to show. Other ideas for different video series that I might do are taking shape so we'll see what comes of that.
Thank you again for watching!