Flash. In Ubuntu you should be able to do something like 'sudo apt-get install flashplugin-installer' to install it and automatically keep it up to date
I found the best way to enable flash content was to get the browser to ask & then let the package manager work it out. Package manager comes up with three options for playing flash, I'd suggest the real Adobe one is the better option although I've used the other open source alternatives & they work ok.
Ubuntu also goes and finds any required codecs, so the first time you go to a media file or media stream it'll take a few moments then will ask if you want it to go & get the media support. Again, I've not had any problems with this & haven't had to resort to command line since Ubuntu 7 to get media support working
BTW rans6andrew
Rans S6 582