When I first started using the 6210 series models I had problems with opening the video files in my existing editing software.
I looked around on the web for free or low cost video editors which were relatively straightforward to use, and found
Video Pad Video Editor from NCH Software.
It seems to support just about everything, is easy to use and is inexpensive to buy.
It can be used free but with irritating reminders to buy the full version.
I hope this helps anyone who is having problems with opening and editing the video files from these cameras.