MTS video files can be accessed by many programs, including widely used media player and media editing software. When you don't have professional video tools, you can play your MTS videos using Windows Media Player. MTS-extension files are video files that contain MPEG high-definition video taken from an HD camcorder. 1 Keep the logo key on Windows, and press the R key to open a new command window. 2 In the command box, type "Explorer" and press Enter to open a browser for the Windows Explorer file. 3 Navigate to the folder where your MTC file is stored. 4 Right-click the file in the folder, and then press "Open." 5 Press "Pick a program from a list of installed programs" button next to the bubble and press "OK" to start. 6 Click on the software list under "Windows Media Player." 7 Check the "Always use the chosen software to access this sort of file" box next to it. Windows should know to access MTS files in Media P...