Rolf,
I did check the “Avoid Pre-Loading Movies” setting and stayed in the thumbnail tab and it did rename the source media. Good call! One more question. I am trying to go back and rename the source media through catalogs that originally would not allow me to. In other words, when I am in the thumbnail tab and rename the clip in the catalog, the option to rename the source media does not appear. Is there some way to get this option to reappear?