Complex sentence: The film was subjected to scrutiny after a video from the set was leaked of a dog being forced into running water, then submerged and requiring human rescue; although it was later concluded the video images were authentic, but had been edited.
Split into simpler sentences: The film was subjected to scrutiny after a video from the set was leaked of a dog being forced into running water, then submerged and requiring human rescue. Resulting investigations concluded that the video images were authentic, but had been edited.