I used MusicBrainz Picard to reorganize hundreds of the files in my music collection. For some reason Banshee spotted that new files appeared, but it didn’t remove the old ones from the library. My library had hundreds of entries relating to files that no longer existed on disk.
I would have hoped that Banshee would just skip when it got to a playlist entry that didn’t exist, but unfortunately (as of v2.4.1 in Ubuntu 12.04) it decides to stop playing at that point. I have to switch to it and double click on the next playlist entry, and even then it thinks it is playing the file that it tried to play before. So I have to double click again.
I have filed a bug about this.
In the mean time I wanted to remove all the dead entries from my library. I could delete my library and re-import it all, but I wanted to keep some of the metadata. I knew it was an SQLite database, so I poked around a bit and came up with this. It seems to work, so maybe it will be useful for someone else.