In digitalized age we are dealing with lots of video formats. Some formats ( avi, mp4) very user-friendly play on any type of devices (DVD players and Smartphones) easily. Some formats not, you can convert the complicated formats to device friendly in Windows.
Video Container Switcher:
Video Container Switcher is a free simple program. The program can convert avi, flv, mpg, mov, mkv and mp4 videos. Input formats are avi, mpg, mkv, flv, mov and mp4, output format which can be mp4 or mkv. The converted videos are automatically placed in the same folder as the source video files.
Handbrake is an open-source video encoder that works with Windows, Mac and Linux computers. The program intended to both rip and convert video files to work on a number of supported devices. It is available for Windows,Mac and Linux. Configuring Handbrake is simple, advanced options are available.
Above two are free programs with ton of features. If you are looking for a paid alternative we have various options available.