Some DVDs play, some don't

[Dave M G]

Ubuntu Users,

I have a set of 5 DVDs, which should be of the same type of encoding, 
although I can't be 100% sure of that. They were burned from ISO images 
using K3B. I don't know if they are DVD +R or -R, or, frankly, even 
really understand the difference despite having it explained to me.

The oddity is that some discs play, some don't. But all play in a 
standard DVD player hooked up to a TV.

The error I get from both Xine and Totem when it comes to the ones that 
don't play is that I either don't have permission, or don't have the 
proper plug ins.

I thought I downloaded every codec and plug in necessary for all media 
types that I could find from the multiverse repositories.

What could I possibly be missing that would stop me from playing a DVD?


--
Dave M G