center frontpage text and video

Wasn't sure exactly why this new design felt awkward to me, then realized it was the left text alignment on the right-side column.

Improvement? @mhjb @rdbartlett 

Before:
![screen shot 2013-11-11 at 10 39 42 pm](https://f.cloud.github.com/assets/1130890/1511649/39fb72e6-4ab5-11e3-8e7d-a62579fa8e5b.png)

After:
![screen shot 2013-11-11 at 10 38 24 pm](https://f.cloud.github.com/assets/1130890/1511650/442e0206-4ab5-11e3-8b40-2e5a454afab2.png)