.avi files will not move to folders.

OK, thank you for the video, it was VERY helpful. 

#1 – I'm not sure what's going on because you are IN that folder but having issues with it. 

so, let's go back to basics, have you done the following?

Go into the System Preferences and select the Privacy & Security tab on the left. Note that there are two options on the right you'll need to deal with: "Files and Folders," and "Full Disk Access."

First, going into Files and Folders, note that in various years of different releases of Adobe Bridge, different needs are needed. I do not know why this is, but it's always better to check and make sure that just because you did it for one release, you may or may not need it for a subsequent release.

Lastly, go into the Full Disk Access option. If you do not see your application in the list, click on the "+" symbol at the very bottom of the window. This will bring up a standard Finder window. Navigate to your Applications Folder, find Adobe Bridge, and add it to the list (You will need to add your Administrator's password to do this.). Then you can "switch" it to the "ON" position. 

I'm guessing here, let me know if that works or not.

And OK, you have a British accent. Where are you from? I'm in California USA.