There is a 10MB file size limit for the Image Library and File Library in a CMS website (No exceptions).  Currently the only workarounds to this are to either condense the file below 10MB, or host the file outside of the CMS website and point to the external file from within your CMS site.

Note: This file size limit was implemented to allow all Organizations the ability to maintain optimum application and site performance, while maintaining server data space allowances.