If the clip doesn't open up in the player, it's likely due either to a configuration problem on the web server or, more likely, a bug in Chimera's support for the system's InternetConfig facility. RealOne Player does set up the system so that browsers should know to hand off appropriate clips to the player, but it is up to the web server to supply the proper MIME type to the browser, and up to the browser to pass the file on to the player.
In any case, you can typically work around the problem by renaming the downloaded file so it ends with a .rm extension and drag that renamed file onto RealOne Player's icon. Alternatively, control-click on the link in the browser and copy the URL link for the content, and then run RealOne Player, open the Open Location window and paste in the URL.
All that's normally necessary to uninstall RealOne Player for Mac OS X is to drag the RealOne Player icon to the trash. If you have admin priveleges and the system isn't letting you drag it to the trash, then there is a problem with Mac OS X permissions, the RealOne Player package file is locked, or the hard drive is corrupt.