Which version of Compressor? The only one you can SEND TO from FCP 7 is 3.5. Any later version and there is no such link. And what do you mean by FCP files?
Best option is to export from FCP 7 as EXPORT>QUICKTIME MOVIE. Don't recompress...and not QUICKTIME CONVERSION. Just QT movie. This will export a movie with the same settings as your sequence. That will be your master. Bring that into Compressor then to compress for YouTube