This article describes how to play .rmvb video files.
The most simple way is to install VLC, which plays .rmvb now, as well as many other video format.
# pacman -S vlc
Next, start it with:
$ realplay &
On the first run, a configuration wizard will set up the necessary options.
Conversion of RealMedia Files
As RealMedia files are not widely (nor well) supported, it may be useful to convert them to another format. FFmpeg can be used for this.
# pacman -S ffmpeg
For example, to convert the video foo.rm to an mp4 file:
ffmpeg -i foo.rm -vcodec mpeg4 -sameq -acodec libfaac -ab 94208 foo.mp4