If you want to share files, upload them or use on social media, you’ll probably find that all of these recommend MP4 files. There may be other formats but MP4 is quite universal. Some formats like flv (flash video) are on their way out as Adobe has stopped supporting Flash. You might also want to convert others like QuickTime MOV files if you find they won’t play on your Windows computer.
The great thing is there is a free media player that you might already use called VLC to play these files, and if you don’t then you’ll be pleased to know it is free and it can be downloaded for either Windows or Mac from here, https://www.videolan.org
In the videos below I show you how to do this. There is a video each for Windows and Mac, they are slightly different.
Converting Using VLC for Mac
Converting Using VLC for Windows
Gary Schwartz's Blog 