How can i change cfr to ...

You can't. (Well you can rename it to whatever you like but it wont play in a media player).

The CFR file is a CrossFire Replay file, it's not a video file. It basically records the movement positions of players, xyz, ect and it can only be played back from the storage part of crossfire.

If you wanted record the file as a video you would have to play it in crossfire and use something like FRAPS to records it.

idk man , sorry ;x