Todd
The first point I would make is that the whole point of LMCE is that it gathers together all your sources of media and presents them in a single common interface so that you can access them and play them from where they currently are. So you shouldn't need to move the video file to the core if you want to play it.
However, if there is some other reason for doing this, then yet it is very easy to use the admin web site (or even just a command line terminal) to do what you want.
I will assume that your LMCE core has already discovered the other PC where the video file is, and has added the share that includes that media file.
In which case, you simply go to the Files & Media menu and choose Media Files Sync. In the left pane you will see the media folder structure as LMCE sees it. Navigate into the first folder which I'm assuming will be Video. Under that you will see all the shares that have been added from remote PCs including the PC where your video is located. Click on that - you will then see the folder structure that is on your other PC. Navigate to the file you want to move.
Now click on the file in the right pane to display its properties. Near the top of the right pane you will see a Move button. Click that. It will open a pop up window, which you can then navigate down through the folder structure again, but this time don't go into one of the share links, stay just under the video folder and click to select that destination.
You can also do the move at the Linux command line using the same folder structure under /home/public/data.... or on the Windows PC by using Network Neighbourhood and navigating into the LINUXMCE workgroup and using just the normal drap'n'drop method - however be aware that these methods will not update your media database automatically. LMCE will perceive the file at the new location as a new video file and in due course update the database with its presence, but not with any tags you may have set in its old location; also it will believe that there is still an old copy in the old location that is "missing" so it will hide it. It is easy to use the admin site to clean up that old copy and to retag the new. But I would still advise using the above method if you are only talking about a small number of files.
