realplay requires libc6 2.5

Binary package hint: realplayer

The most recent version of realplay requires libc6 >= 2.5-0ubuntu1. This is not available in edgy, the latest in edgy goes only to 2.4-1ubuntu12.

Paste from apt-get install realplay:

rlipman@aiur:~$ sudo apt-get install realplay
Password:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.

Since you only requested a single operation it is extremely likely that
the package is simply not installable and a bug report against
that package should be filed.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
  realplay: Depends: libc6 (>= 2.5-0ubuntu1) but 2.4-1ubuntu12.2 is to be installed
E: Broken packages