reverting -movflags

FFMPEG -movflags faststart is creating a bug with certain large files
where writing the moov atoms after the faststart processing causes
playback errors. This was seen before with qtfaststart. Only 100%
solution seems to be to move the atoms after tagging.
limit poster size

movie poster sizes limited to 500px width instead of full size (could be
upwards 3-4 mbs per image previously)