That's because he use Chrome on Windows, who doesn't render webfont well due to the usage of GDI instead of DirectWrite in the Windows version: https://code.google.com/p/chromium/issues/detail?id=137692
Here's a screenshot of nightly with a similar issue. http://i.imgur.com/HP02e5b.png
Even this, with the font stripped out looks better http://i.imgur.com/6KB2iuG.png
If you adjust your cleartype settings (or turn it on in XP) it will look a bit more normal.