The party seeking to make use of a photograph or video bears the burden of "authentication." This means they must establish that the photo or video depicts the relevant event and has not been materially altered. Even if there are changes or alterations, if the image or video is substantially accurate, and is a fair representation of what it purports to show, the evidence may be admitted.
Video or image evidence can be "authenticated" on the basis of direct or circumstantial evidence. It is usually sufficient for the person introducing the evidence to call a witness who can say they took the photo or video and that they did not alter it.
When deciding on admissibility this threshold of "authentication" is a modest one: the party seeking to admit the evidence need only provide some evidence capable of supporting a finding that document is what it purports to be.
For a summary of these principles, see R. v. Chaudhry, 2021 ONSC 6589, paragraphs 13-18.