Why can I only add video file to Home Video folder

I’ve just started using Plex on my WD Home Cloud drive and my iphone. It’ s really cool but I don’t understand something despite reading everywhere.

The installation of Plex I have came with some pre-made directories like Movie, TV Shows and Home Video.
I have an .mp4 video file named correctly title (date).mp4 but I cannot understand why this video file is only visible when I put it in the Home Videos directory but remains hidden if I put it in the TV Shows or Movies directory. Why is this, what does Plex care?
I actually want to put it into a directory called Documentaries that I made but it’s not visible there.

Many thanks.

Did you review this

Plex has different kind of libraries with different agents that scan the media assigned to each kind so for instance a TV shows library might use TheTVDB as an agent to get data from the internet for TV shows where as a Movies library might use IMDB to get movie info.

Since personal home videos require no agent to collect metadata they are treated differently. You can adjust your libraries to use different agents under this screen below located at Settings --> Server --> Agents:

You should be able to add new libraries and define their type i.e TV or Movie, for the most part documentaries I watch I store under movies and my movie agent is able to find the information about it so this way I do not have an extra documentaries library but that is all up to you.

I hope this explains what you are asking.

Excellent answer, very clear and helpful. Thank you.