Two things to keep in mind while looking for Sasquatch, especially while reviewing photographs and video, are parallax and pareidolia. These can play a considerable role in perception sometimes. It has been recommended to always go back to areas and try to recreate the scenario (time of day, position, movement) to see if perhaps either of these are at play.
Parallax is defined by Dictionary.com as “the apparent displacement of an observed object due to a change in the position of the observer” or “the difference between the view of an object as seen through the picture-taking lens of a camera and the view as seen through a separate viewfinder.” The great example that Wikipedia.com gives is “the dashboard of motor vehicles that use a needle-style speedometer gauge. When viewed from directly in front, the speed may show exactly 60; but when viewed from the passenger seat the needle may appear to show a slightly different speed, due to the angle of viewing.”
Pareidolia is defined by Merriam-Webster.com as “the tendency to perceive a specific, often meaningful image in a random or ambiguous visual pattern… or the human ability to see shapes or make pictures out of randomness”. For some great examples of pareidolia, check out this photo-list regarding examples in outer space, or this one on seeing faces in commonplace items.