He was likely using something like an Erogtron wall mount. They are commonly used in hospitals as well. Check them out: http://www.ergotron.com/Products/WallMounts/tabid/157/Default.aspx

There are cheaper alternatives out there. But to be honest, nothing really matches these arms. I have 3 on my personal computer. And my dad has one on his as well. Full range of motion. Good extension. They are awesome. Lets me fit 3 monitors on my desk.
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