This sentence has two possible interpretations: 1 They weren't shown this video clip... means 'no one showed the video clip to anyone in the group 'they' (the people to whom 'they' is referring)'. 2 They weren't shown IN this video clip... means 'some people or some things, i.e., 'they' were not shown (did not appear) in the video clip.

No. They weren't shown this video clip.