Although the camera lies it takes quite a bit of dosh to "photo shop" 25/30fps video and even more to do it seamlessly without proper pre-planning.
Access to the original recording is the number one goal to build a defence.
It is possible to analyze a video by tracking horizons and creating a 3d terrain map ect to establish where the camera is in relation to the ground.
Camera phones are relatively easy as they have a fixed focal length although most suffer from rolling shutter artifacts which often distort the image when the camera is wobbled around.
Mickjoebill