You may for many reasons not choose RealOne player to play RM/RMVB files: it launches many unnecessary processes in the background, displays unwanted web pages, and uses too many system resources.

There are many programs to play RMVB files, among them we recommend KMPlayer, or Media Player Classic. Both of them are filter based player, so you can use them to play files of any formats provided that you have the right codec installed. To install rmvb codec, you have two options:

1. Install RealOne Player. The installation will copy the rm/rmvb codec in your system folder. You can then use [Media Player Classic to play RMVB file.
2. Download and install the RealAlternative codec. (Where to download? Google RealAlternative and you will find tons of download links.)