The 402G comes with a CD that has bespoke software that uses all the features of the unit. There is a Windows version and a Mac version. If your computer doesn't have a CD player (like my Macbook) you will need to transfer your version of the software onto a USB stick from someone elses computer, or download it from the Nextbase website; and then install it on your computer.
From memory, to install it on the Mac you click on the .dmg file, then drag the program into your Applications folder.
On a PC you would run the Setup file and follow the instructions.
This is what the screen looks like with the Driving Recorder Player (on a Mac
As well as the movie, you can see there is lots of other information there like direction of travel, location on Google maps, direction of any impact, sound waveforms so you could see a bang etc. As the movie plays you can see your location moving on the Google map - pretty cool I think!
Even if you have installed the correct software, when you plug your cam or SD card into the computer, the computer sees it as media files and may think that you are uploading your holiday snaps and movies and want to view them on your default program; and you will only see the movie file.
When you plug in the dash cam you have to close the default program, and open the files with the Driving Recorder Player. If you have XP or similar, go to the Start menu, Programs and look for it in there (there might be a shortcut on the Desktop). If you have a Mac, from the Finder click Go > Applications > Driving Recorder Player (we'll call it DRP from now on).
Once DRP is running, go to File > Add Filelist and navigate to where your dash cam files are and select all of them. After that it should be straightforward. (?)
Hope this helps anyone who is stuck.