[ubuntu intrepid] Guest cannot watch flash in firefox when flash-plugin originally installed via firefox

When the main user is running firefox on a fresh instll and tries to watch a flash video e.g. on youtube, it does not work because the plugin is missing. That user can install those missing plugins as offered by firefox, and it works. However, when switching to a "Guest" account, the flash plugin is NOT accessible by the guest; flash videos do not run. The missing plugin install is offered again, but eventually fails (understandable as the guest should not modify anything, but why is it offered then?).

Checking under Synaptic I find that the Adobe Flash Player plugin is offered twice, and none is checked as installed. Installing the "adobe-flashplugin" from the archive.canonical.com/partner repository eventually allows both user and guest to watch flash videos.

The second offer is "flashplugin-nonfree" from the multiverse repository. I was unable to figure out, if there is any difference to the one I installed (I did not try it), but believe there is not. Then why is the same thing offered twice under slightly different names? One should should be removed, as it is only confusing. And if there is a difference, it needs to be made clear what it is.

And actually there is a third way, which resulted in the error I described above. This one is the "natural" way for a user to install the plugin, and should be installed in a way to allow all users to use it.

~$ uname -a
Linux aa1 2.6.27-8-generic #1 SMP Thu Nov 6 17:33:54 UTC 2008 i686 GNU/Linux