So, since the pictures and videos turned out not to be the problem, and even though I have indicated in the application manager that I wanted all apps that were eligible to move to the SD card to move. I still find myself with more than 90% of the phone's 16 GB full.
I deleted the Kindle reader - I only had one book on the phone - and that freed up a few MB.
I guess I can go through and delete even more of the apps that I don't use that much. I have about 125 apps (which includes all the stuff that came out of the box and that I don't use right now).
When I look in the application manager > storage > space used, it says 9.21 GB is used.
8.7 GB of that is used by Applications.The 6 largest together use less than 1 GB. Of those, 2 are games and the rest are bits "of the system" (facebook, chrome, yahoo mail ,and google play store).
The other 7 GB is spread across all the apps, services, etc. that come on the phone (well, except for a dozen or two apps each less than 100 MB that I've downloaded).