A dvd cannot be played out of the box on a freshly installed system. The reason being that all DVD's are encrypted with CSS (Content Scrambling System). CSS uses a variety of keys (string of characters) that authenticate the dvd being read by the player. Now to be able to play the dvd, the player must be able to decrypt the data.
The reason that most free players dont come with this codec is because it is being contested in the couts that such plugins are illegal and inorder to use them a license must be bought. (Makes me grind my teeth) !!, and as far as i know, no decision has been arrived yet (atleast I think !).
Check this link for some additional information.
Well so now you know, why we need to go through all this additional hassles when we use free players on Linux. We dont see this problem in windows, coz windows media player comes bundled with these codecs and the cost is worked into the price of the windows operating system.
And as to how to play movies on dvd, check the following link: http://doc.ubuntu.com/ubuntu/desktopguide/C/video.html
The instructions are pretty comprehensive.
Had to install the win32 codecs too, so that I could play the movie. Hmm..wonder whether the reason I couldnt play the movie with totem initially was because I hadnt installed the totem-xine player :? !! Anyway dvds are rocking on my machine now :| !!