Problem occurs with:
* Ubuntu 8.04 LTS
* Ubuntu 9.04
* Ubuntu Karmic, all updates installed
1. From a fresh Ubuntu installation, go to <http://www.youtube.com/>.
2. Go to any of the videos.
What should happen: Firefox's plug-in finder bar appears.
Ubuntu's plug-in finder bar works only for <embed> elements, and therefore it is working for fewer and fewer Flash sites over time.
A simple solution might be to hack firefox to always provide the information that the flash capability is present, even when the flash plugin is not yet installed. Therefore, the site would provide the flash object, and the automatic flash plugin installation would kick in.