It is possible to open Local Files outside Media Folders and thus are not visible in Resource Tree.
Use one of the following:
•Drag-n-Drop one or several video files from Windows Explorer to Nx Witness window
•Drag-n-drop a folder containing video files from Windows Explorer to Nx Witness window
•Open Main Menu and choose Open –> File(s)… (or use Ctrl + O) then choose the file(s) to be opened
•Open Main Menu and choose Open –> Folder… then choose a folder to be opened
•Invoke Context Menu on Scene (on empty space) and choose Open –> Folder…, then choose a folder to be opened.
Any opened files will be shown in Resource Tree until Nx Witness is restarted. If restore Layout that contains Items located outside of Media Folders they will be restored in Resource Tree as well.