This video is presented as "Impel Down-hen (インペルダウン篇まで) (PV)" on your link, where they explain, I quote : "PV stands for Promotional Video, more commonly known outside of Japan as a music video."

Music videos aren't supported on TMDB.

In fact, it's not a music video, it's really pieces of episodes stuck together to sum up the show up to the Impel Down arc. I'll understand if you don't want to add it, but I really think it should be there. It's very frustrating to set up a Plex server for this show, no compatible database matches what I need T_T

It shouldn't be added here for 2 reasons:

• It is released on an OST (Original Sound Track) CD/DVD box, not on a DVD of the series itself.
• If it is just pieces of episodes stuck together without anything else, this is considered as duplicate material.

There's also new musics and new video editing and it's clearly linked to the serie but yeah whatever, you're the one in charge so you decide. Any chance to add it as a standalone movie, the same way soemone did it for OVAs or even the Theme Park 3D stuff ?