Intellex Digital Video Management is a system designed to help you keep track of and record several different video cameras at once for the purpose of monitoring a particular area. IMG is an electronic backup of a physical CD, such as one you've recorded with Intellex. If you want to convert IMG files back to their original video format, such as AVI, you can do so using free virtual CD software as well as native tools in Windows.
Download and install a free virtual CD program (see Resources). Open the program and click on one of the virtual drives. A browser window appears. Double-click the IMG file you want to mount it.
Click "Start" and select "My Computer." Open the virtual drive listed there. The IMG CD opens, showing you the videos on it.
Click and drag the video you want to your computer's hard drive to "rip" it from the CD.