In the case of this video, Monbiot speaks of 'deer' and then shows pictures of American Elk (Cervus canadensis). This is defensible, as he's British, and the European Red Deer (Cervus elaphus) is very closely related and likely more familiar to his anticipated viewers. But midway through, the video cuts to pictures of a Mule Deer (Odocoileus hemionus), which an expert is unlikely to conflate with an elk.
This could be considered an "irrelevant" detail, but one of the major differences is that the American Elk primarily graze as they have a digestive system that allows them to efficiently digest grasses, but the Mule Deer do not: they eat some grass, but primarily "browse" on woody vegetation. So while they will both have an effect on streamside vegetation, it's going to be a very different effect.
In a piece that purports to explain the science behind the cascading effects of wolves on the ecosystem, this feels like a disconcerting blunder. Should it cause me to doubt the credibility of the piece as a whole? I don't know. But it makes it more difficult for me to treat Monbiot as an authority on the topic.
That wasn't clear to me. Rather, I presumed (I think reasonably) from the tag "Sustainable Man Original" that it was something that that Monbiot had participated in the creation of. I've now read the comments on the Sustainable Man page (http://sustainableman.org/blog/2014/02/17/how-wolves-change-...), and see that other have pointed out that the video also uses uncredited video of English badgers and Slovenian bears.
The creator of the video responds "Hi, we “steal” footage from lots of sources all in a non-commercial effort to raise awareness about sustainability.". The removes most of the criticism I'd have toward Monbiot, and retargets it toward Sustainable Man. The video is clearly more concerned with rhetoric rather than accuracy. Regardless of the goodness of the cause, I think in the end this sloppiness with facts will do more harm than good.