How to install iDVD from the internet (MacBook Air 11" mid 2011 model)
I downloaded and installed PACIFIST from here http://www.macupdate.com/app/mac/6812/pacifist
Pacifist is a install package extractor.
Then I downloaded an iDVD upgrade package from here:
http://support.apple.com/kb/DL1353
When installing the upgrade package you will get an error saying the you have no qualifying application installed.
Do the following:
Use Pacifist to extract the iDVD.app file from the upgrade package to your Applications folder.
If you try to use iDVD now it will complain about missing themes.
First install some free themes from here: dvdthemepak.com
If you open iDVD now you will see some gray themes below those you installed. Click on one. iDVD will update itself. Afterwards click on one of the gray themes again. iDVD will download those themes. (> 500 MB)
I wrote a DVD using an external LG writer and all seems fine.