Before we can display Media-based images in a Colorbox, we need to install and enable the module.
$ drush dl colorbox-7.x-1.x-dev Project colorbox (7.x-1.x-dev) downloaded to [success] /Users/kurt/htdocs/d7dev/sites/all/modules/colorbox. $ drush en colorbox The following extensions will be enabled: colorbox ColorboxColorboxinstallingDo you really want to continue? (y/n): y colorbox was enabled successfully. [ok]