About 2 weeks ago or so, I stopped being able to watch any Amazon Prime video on my Ubuntu 12.10 box. I was fine previously, after installing HAL and disabling the Pepper flash plugin in Chrome, so the Adobe plugin was used. But suddenly, with Flash 11.2.202.280, it didn't work.
After experimentation, I found that video viewing was re-enabled by back-leveling to an earlier Flash plugin version. Instructions
here.
Can't try it till tonight, but hopefully that workaround is effective still. Minor edit to the instructions, I later tried the plugin version right before 11.2.202.280 (can't recall the number) and it worked fine
... probably better than back-leveling all the way to 10.1, like I mentioned in those instructions.