FCP -> YouTube: best settings
Look to Phillip Hodgetts, an expert editor and consultant based around FCP, if you’re seeking to upload your video(s) to YouTube. Phillip has a short write-up and a link to an example of pretty rock-solid settings that will get you closer to the quality you want to show (but that YouTube doesn’t want to support as it’s $$ in bandwidth).
Link: Phillip Hodgett’s YouTube article on the LA Final Cut Pro User Group (LAFCPUG) site.