english: The tricky part is that those signals, those changes that we're after, are extremely subtle, so we have to be very careful when you try to separate them from noise that always exists in videos.
non_english: Najteži deo je to što su ti signali, te promene koje mi tražimo,  neverovatno suptilne, pa moramo da budemo jako oprezni  dok ih razdvajamo od smetnji iz svih tih snimaka.