Traditionally I needed real player 10 to get it to work. But that is too old to be installed on windows 7 64bit. Thus, I had to install real alternative and k-lite and stuff.
Per k-lite (http://www.codecguide.com/faq_playback_issues.htm#item32):
You are missing a decoder for RealAudio COOK. You can install that by following these steps:
- Download the Windows version of binary codec pack for MPlayer.
http://www.mplayerhq.hu/design7/dload.html#binary_codec
(filename = windows-essential-20071007.zip) - Extract only these files from the ZIP archive:
cook.dll, pncrt.dll, sipr3260.dll, drv33260.dll, drv43260.dll - Put those files in the Windows system folder.
That is C:WindowsSystem32 on a 32-bit version of Windows.
That is C:WindowsSysWOW64 on a 64-bit version of Windows.
After that, I can view rmvb files with the kmplayer