There's ffmpeg.

https://www.ffmpeg.org/

It's a mature open source project, and has been included in Linux distributions for a long time.

In my opinion, unless you are converting for a specific purpose, you don't need to go converting videos.

Here, use this. It's the codec pack I use, since I watch anime and video stuff which requires the right codecs be available. Just follow the instructions and install the player that comes with it. Use the player. It has almost all formats known to earth and displays subtitles well.

http://www.cccp-project.net/

deleted

Handbrake is pretty good for that kinda thing.

I second Handbrake.

Handbrake is probably the ultimate answer to video converter

The other swiss army knife of video converter is WinFF

deleted

Handbrake outputs the mp4/mkv container. However, yes! It contains the Mpeg codecs. You can choose mpeg from the dropdown menu under "Video Codec". That reminds me, what is it exactly are you trying to do? Because from what you said later, you are not just watching a video, but wanting to do some editing stuff?

And here I always thought you were one of those broken spam bots with a mucked up English dictionary. :)

Gotta admit that I just use VLC's built in conversation system. I rarely do one though. Been like over a year since the last one I did.

deleted

handbrake, like recommended by others, is for people who are inexperienced. If you know what you want, megui might be better. However, it would be nice IF YOU TOLD HE WHAT YOU WERE TRYING TO DO so we could maybe point you to what works beter.

If you don't mind the AVI container, i like VirtualDub, good for basic editing and converting and encoding. Not good for lots of advanced effects.

The other i'd say is ffmpeg, but dtgreene in post #2 already suggested that.