I am sorry if this subject has already been covered, but I find that I can't add some MP4 video's for editing. Some load OK, others not.....is there a patch or upgrade that will allow X6 to accept/process these files ?
FWIW, I produce mp4 high def 1920 x 1080 i and p video with both my GoPro Hero 3 and Samsung Galaxy SIII smart phone, and have no difficulty at all in inserting and editing my videos, and even producing new mp4s -- and other formats -- from them. So yes, it would be useful to know exactly where your mp4s came from.