It's going to be some sort of custom hard drive format, it's not formattet in a way that windows/macos will read out of hand.
Isobuster should be able to red and give you the video from the hard drive if you remove it from the recorder and you have some way of plugging it into a computer (you can get cheap IDE (it's old enough to be IDE, not SATA) to USB adapters on
amazon, ebay or wherever else that sells computer stuff).
Whether these will work fine if you were to replace the hard drive with some sort of setup with a SD or other flash card I don't know.