FCP X does not have the option to burn in Source Timecode into a clip. This is often needed for dailies or for sending preview versions to producers or clients. This free plugin from CoreMelt will allow you to burn in source timecode into the clip easily and export it. Now has the ability to burnin filename and shot number as well.

Source Timecode is available in the CoreMelt FREE plugin installer together with over 40 other free plugins for FCP X.