So, after days of screwing around with varying instructions, I finally got my Samsung Chronos 7 video working. This laptop uses an intel/AMD hybrid graphics:
$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Seymour [Radeon HD 6400M/7400M Series] (rev ff)
As described here: https://wiki.ubuntu.com/X/Config/HybridGraphics , All I had to do was remove all fglrx related packages, remove the xorg.conf (I never had one before anyway, move yours somewhere safe if you want a backup), purge packages from other xorg PPAs, and install fglrx and fglrx-pxpress:
After that, my AMD graphics was working for the first time (e.g. I could run glxgears, and fglrxinfo). But the AMD card was causing really glitchy graphics, so I used AMDCCLE to switch to the internal car (intel), which works well.
sudo apt-get purge fglrx*
sudo ppa-purge xorg-edgers
sudo rm -rf /etc/X11/xorg.conf
sudo aptitude install fglrx fglrx-pxpress
The computer now runs about 10-15 degrees hotter than it did before. I'm not sure why that is - the link above mentions that this will happen for nvidia, but not for AMD, but maybe it's something similar. If anyone knows how to cool it back down on the intel GPU, or stop the glitching on the AMD GPU, let me know.