Comment 42 for bug 125986

I interpreted your instructions as meaning to manually edit the sources.list file to add "multiverse universe" to the line that mentioned the feisty-updates. After doing this, I started Synaptic and did a reload, and it now told me that four packages needed to be upgraded, including the flashplugin-nonfree package. When applied, it did not download the Flash package again (so it must still be cached locally), but it did announced that the Flash plugin was installed.

Unfortunately, that does not seem to have resolved the problem. Still no Flash content.