In majority of cases following instruction in step 1 should be enough to open files with M1V extension. What is file extension M1V? The M1V file extension is associated with the Moving Pictures Experts Group video MPEG-1 video compression file format. The first step is to check if the computer has the QuickTime Player program installed. Windows Media Player, a windows default media player, is capable of opening and playing M1V files. The data in the M1V files are saved in the manner characteristic for Video Files. The extension informs us about the type of the file content. Later in this article you will find a list of programs that can open M1V files. Step 2 – Install a program that supports M1V files. Various programs can open an M1V file. Our tools for working with the M1V file. 1. M1V File Opener. Be careful with .m1v files. List of all softwares that can open the MPEG-1 Video File.