The media has NOT been stored within the FTM data for many versions. It is in the "C:\Users\username\Documents\Family Tree Maker\'FTM dataFile Media' " folder.
So by removing the Media will not make the data file any smaller, but if you were to remove the media and LINKS then the file may be reduced.
Also note that some of the media is also located at Ancestry and when the sync is being made, they ALL need to be checked to make sure the changes in the media is also synced.
The media WILL take a long time to do.