TheMovieDB has them for some concert DVDs.
So it is worth doing a search there
If it is listed, change the file name/folder name of your rip and perform a manual ‘Match/Fix Match’ with TheMovieDatabase selected as the ‘agent’.
https://support.plex.tv/hc/en-us/articles/201018497-Fix-Match-Match
It is is not listed, perform a manual Match with ‘Personal Media’ selected as the agent.
Then put in the metadata by hand.
More about concert videos:
https://forums.plex.tv/discussion/comment/1118231/#Comment_1118231
