A plug-in for Totem (Ubuntu’s standard movie player), released in January, allows to stream video via Apple’s AirPlay. I checked it out immediately, and it worked. With the release of Ubuntu 11.04, it stopped working. The plugin couldn’t be activeated and Totem gave out the error message
Unable to activate plugin AirPlay Support
Then, I found the solution, a comment on the very same article I linked to above. Like Paul Kehle says, once you install ‘avahi-discover’, it works. Run
sudo apt-get install avahi-discover
in Terminal and you’re fine. Thanks, Paul.
I just wanted to share this because I’d given up hope and just came across it by accident.