Your assumption is correct, you can install a program in the root home directory and with the proper permisions, anyone would execute it. However, the standard location for programs for all users is /usr/bin, or even /usr/local/bin. The root owned programs are usually installed in /sbin or in /usr/sbin. This is a custom but not mandatory or applicable in all the cases. For example, if a program is distributed with its own libs, or needs some sub-dirs to work or files associated with the binary, I like to have it in /opt so I can keep /usr/bin clean. In this case I would put realplayer in /opt and place a symlink to /usr/bin which is in the path of all the users. It is also the custom to place in /opt the big programs like kde or open office. I extend this usage to any static binary.