Burning pretty much anything with K3b is very easy, dual layer DVDs too, I experienced. So far, so good...
The problem came when I wanted to verify the DVD: "Sorry I can't read the media", openSUSE tells me. Seriously - I can burn it but I can't read it!?
Alright, it also tells me: "Would you like to install the software needed?". I click "yes, of course!".
Fail. "I can't find it but you can look for it yourself here". "Here" being a link to a very general page about repositories.
Sorry, openSUSE. This is not what I need. I did look around for whatever it is I need at opensuse.org and with YaST. No success. No doubt I can make it work. (Perhaps even faster than typing this blog post but that's not my point.)
I then put the freshly burnt dual layer DVD with my precious data backed up on it into my Mac. Two seconds later I'm watching one of my videos.
Thank you Mac for doing something that quite obviously should be possible with any computer. Thumbs down to openSUSE for not even warning me of a only partially functional part of my hardware setup during install. Sure hope upgrading will fix it without me having to mess around with the system.
(Disclaimer: If dual layer DVD technology is evil and will never work on open source systems, please enlighten me.)