The .mv2 file is video only. It should be accompanied by a file with the same name and the extension .wav.
It just means the video and sound are on separated files. But it is a normal procedure.

Update. Well, even burning at 2x (the slowest setting) the dvd-r still won't play in my neighbor's pioneer player, even though it plays fine in every other player I've tried.

Also discovered that rendering solid black after the credits only takes a faction of the time compared to rendering video.

And I solved the temp file error by freeing up more space on C drive, though I never did find exactly where these temp file folders were.

Thanks for all the advice and tips, I think I'm starting to get the hang of dvd burning now.

Try looking up that Pioneer here http://www.videohelp.com/dvdplayers

Enter Pioneer and the model number or search through the results. Anything struck out means that a respondant could not get that media to work in that player. Light Grey either means not tested on inconclusive.