I understand it's a review of the 45 minute episode, not the 30 second trailer. Having seen the episode, the "heart" of the episode is certainly not in any of the trailers.
I haven't seen this review, but 1% of the total runlength for a review seems quite reasonable.
Apparently it's quite common on youtube for people to take entire pieces of someone elses work (like 30 seconds of a 30 second piece), say "hmm, that was interesting", and post it online. MxR Plays v. Jukin [1] was a recent case, where they refused to pay the really reasonable license fee for the video, posted the video in full, said "no, not funny" or something, and then sold it for profit. The original video is something like 10% of the entire piece rather than 99%.
The couple of question then posted videos admitting they were breaking the law. My knowledge of this case mainly comes from LegalEagle reviewing it [2]. To me they haven't got a case (unlike this angry joe guy), but apparently they might have.
[1] https://www.bbc.co.uk/news/blogs-trending-51090857
[2] https://www.youtube.com/watch?v=5A_i-sB9H0Q