Name Dropper 3.4 and up has the ability to preview most Quicktime and Real Media files, provided that the appropriate DirectShow Filters are installed. Luckily there are free utilities that provide these filters, as well as offer an alternative to the sometimes intrusive "official" plug-ins!
Quicktime Alternative - Recommend version 1.53 as file compatibility problems had been reported with a few versions soon after. It may have been fixed though.
Real Alternative - Recommend version 1.45 or newer