You gave no details about the DVR or the file formats so it is impossible to say you can't. If you do succeed of getting your TV programs from one DVR to another by any method, you will be the rare exception.
Probably not... most DVR makers code to the hard drive in a proprietary format that will not work in any other DVR
You may be able to PLAY the video out to an external recording device, such as a VCR or a DVD recorder
Or, for a computer, you may be able to use a converter such as at http://www.grassvalley.com/products/converters