Just google search Step by Step Guide on How to Convert MP4 to DV so as to Import MP4 into FCP/FCE
You will find a detailed guide on how to convert and import MP4 to FCP/FCE:
It is dead easy to import MP4 into Final Cut Pro for editing with the following guide.
It applies to MP4 recorded from various camcorders like Samsung HMX-H100 camcorder, Sanyo XACTO HD1000 Full HD camera, Flip camcorder, JVC GY-HM100, JVC GY-HM700 and more.
It applies to MP4 from media players, mobile phones, portable devices and YouTube etc.
It also applies to import MP4 to Final Cut Express and iMovie.
It applies to import MP4 to Final Cut Pro X or import MP4 to Final Cut Pro 7 or import MP4 to any other version of Final Cut Pro.