Change medium|large breakpoint from 64em to 59em
Set row-width so that video dimensions = 800x600 (large grid)

Vimcasts videos are recorded at 800x600 resolution. Zurb Foundation
defaults caused video element to have 803x602 dimensions. So close!
I assume that the browser has to work hard to scale a video, so it's
desirible to use native video resolution if possible. This change
modifies row-width, therefore touches everything, so it might have
unexpected consequences. Hope not!
Ensure that video doesn't scale above 800x600 in medium layout
Style "Run time" as though it were an <h4> (medium+small grid)
Use topbar navigation on medium grid (as well as large grid)
Remove "Vimcasts" from the top-bar navigation

The Vimcasts logo serves as a link to the homepage, so we don't need
the title in the menu bar too. Plus, this frees up space. We'll be
adding more items to the menu one day.
Add a search field to the menu bar in small layout
Make medium/large grid search form occupy 1/3rd of container