"I searched for SDL and found a package for it and installed it. However, even though that is installed FCE is still giving me that same error message that I need SDL12 installed."
I can think of two possible reasons why you are still having problems with SDL.
1. The version that you installed is not the one that FCE is looking for.
2. You may have installed SDL from a tarball instead of a rpm. In that case SDL is installed but not recorded in the rpm data base. If you are sure that you have the proper version of SDL installed but it is not in the rpm data base then you can install the FCE rpm using --nodeps. See man rpm for a description of --nodeps.
Also if you are compiling a tarball you should consider using checkinstall to change the tarball into a rpm:
Be prepared. Create a LifeBoat CD.