A different fix! (if you have customized Sort fields)
For me the problem was not video podcasts; it was that I had customized some of the new "Sort" fields introduced in the last version.
I could tell it was a problem because I had used the sort field to sort by last name (for example "Simon, Paul" instead of "Paul Simon") and it was sorting by "Paul Simon" even though the sort field said "Simon, Paul". But after opening the information panel and hitting OK, it did sort it by "Simon, Paul". So then I had two Paul Simon entries, one for P and one for S.
I then fixed all my entries by viewing all the songs, going to information for the first, and clicking Next all the way through. Boring but it worked! I also only had about 800 songs, so it wasn't actually too bad.
And after that it was able to write the library!
I also want to comment that the new version does the "right thing" more often when you're using the new Album Artist tag; if the Album Artist is the same for all tracks in an album even though one of the tracks might be different, in the Artist listing only the album artist shows up. For example, I have a BBKing album with a track by "BBKing and U2"; it formerly had both listed under Artist, separately. Now only BBKing is listed, because BBKing is the album artist for all tracks! However, I do have one album that it guessed the artist name wrong, so to use the above example, it was calling "BBKing and U2" the artist for all tracks on the album instead of just "BBKing". But generally I'm more pleased with the sorting in 7.3 than in 7.2.