Montage & Music
Here is the most creative part of the job. Movies were destroyed here and other mediocre ones shined through it. So be carefull. Not to destroy our footage. And because a mediocre photo or film never became excelent through photoshop or montage, then please do not rest through filming. The montage can fix some things and make a mediocre documentary to a good one but it surely can't make it as good as perfect. So music is 50% of the film and the other 50% is pictures.
A film shouldn't be too long because it is tiring for the audience. It is better for the viewer to say <<Oh was it really this much? Doesn't it have more? Is it really over?>>. That's why it is better most of the times to remove things and not add unnecessary ones.