Video shouldn't be a cover. Especially in a single-video article.

This image is a part of the slideshow, it shouldn't be treated as a cover. And more importantly, the second image is missing. Also, these images have captions.
Regarding the other video-cover issue — it was more of a recommendation. Sure the rules say it's optional, but it's preferred not to treat videos or gifs as a cover.
Cheers!

This image belongs to the slideshow in the beginning of the article. It shouldn't be a cover. It also misses the caption. And the second image is just missing.

Cover image is missing

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