When fiberglass is pushed up into the space between the floor joists around the perimeter of the basement, condensation often builds up on the wood behind the fiberglass. This can be stopped by the addition of an air barrier -- as simple as Kraft paper or as complex as caulked polystyrene. In practice, a paper barrier without caulking around it, will protect all but the most humid of basements.
If your house is built with the joists embedded into the cement wall, you should not insulate this area at all. Sorry about that, but you just can't prevent some moisture damage to the ends of the joists if you don't allow a planned heat loss to this type of header area. These houses could, however, be safely insulated from the outside as such an approach would leave both the header and the concrete wall warm and frost free.