What you should do is to copy the vids from the SD card to your PC hard drive. Then you can play/edit them. If you start tweaking images/vids on the card, you may lose the file(s). That way, you always have a "Master Backup".
If you are using a PC, then it should play natively, whether either .Mov, or .Mpeg format. Just be aware, that if you have an older PC, say 3/4 years old, it may not play 4K smoothly, and it also helps to have a dedicated video card, the older integrated video cards usually cannot handle the 4K bits. You may have to drop down the the 2k format if your PC , is, say a wee bit on the elder side.
Also, you can switch to either .mov, or .Mpeg in the app when it is connected. Remember, all setting in the app only change and save if you are connected to your Mavic/RC