Sample from log file:
2015-03-10 18:30:40,924 (1318) : DEBUG (logkit:13) - Found valid file #13 named: H:\Musique\David Bowie\Best of Bowie\Scenes\Be My Wife.mkv
2015-03-10 18:30:40,924 (1318) : DEBUG (logkit:13) - Found valid file #14 named: H:\Musique\David Bowie\Best of Bowie\Scenes\Black Tie White Noise.mkv
2015-03-10 18:30:40,924 (1318) : DEBUG (logkit:13) - Found valid file #15 named: H:\Musique\David Bowie\Best of Bowie\Scenes\Blue Jean (alternate version for MTV).mkv
Local extras are wrongly flagged as 'Unmatched' when the metadata agent of a library is set to 'Personal Media' AND those extras are marked using the subfolder method (as opposed to the -suffix method) https://support.plex.tv/hc/en-us/articles/200220677-Local-Media-Assets-Movies
Sample from log file: 2015-03-10 18:30:40,924 (1318) : DEBUG (logkit:13) - Found valid file #13 named: H:\Musique\David Bowie\Best of Bowie\Scenes\Be My Wife.mkv 2015-03-10 18:30:40,924 (1318) : DEBUG (logkit:13) - Found valid file #14 named: H:\Musique\David Bowie\Best of Bowie\Scenes\Black Tie White Noise.mkv 2015-03-10 18:30:40,924 (1318) : DEBUG (logkit:13) - Found valid file #15 named: H:\Musique\David Bowie\Best of Bowie\Scenes\Blue Jean (alternate version for MTV).mkv
notice the 'Scenes' subfolder.