Moving & Deleting Files dont work - Please help

I want to move files in one folder on the Homescreen. For example all Bud Spencer movies, all Marvel, all Kids movies in a seperate folder.
If i do it like in the guide, my select button is grey and i cant push it. Is there a trick or a special folder structur on HDD needed?
My HDDs are on a FritzBox 7490 via SMB. Is there anyone who could help please?

Sorry for my bad english;)

Welcome to the forum!

The option to move videos into folders actually only works with local videos. For streamed videos, your best option would be to create your own folders and add these as Favorites which would be visible via the Files screen. You can also add specific genres which would appear on the Library screen. More info on adding Favorites can be found here. Managing Favorites & Lists – Firecore