Amazon Prime

Ok, so for several reasons it made sense to take up the Amazon Prime ecosystem a few weeks back. The only problem is, I can't seem to play Prime video > 960x540 on any HD screen no matter what I do (seemingly browser agnostic, user-agent spoofing etc).

Has anyone managed to play 720p or greater on a Linux based system? If so, can someone share the recipe for the sauce? Grassy-arse.
- Colsta