Video play icon fix

There was a 'bug' causing play icon to appear broken on the large items:
![screen shot 2014-11-19 at 15 05 37](https://cloud.githubusercontent.com/assets/2579465/5112170/b55e3480-701d-11e4-865c-0a1ac5be2096.png)

It seems that we were not using the default x-small icon so I've changed it to the small version. @michaelwmcnamara looked at it to and it seems to be ok.

The main reason why I did that instead of adding breakpoints for `mega-full` class, is to not add more css if it's not really necessary. 

CC @sndrs