Any piece of evidence is just a start in factchecking. Video evidence, just like text, can be misleading — it can be video of footage of a different event than what is described in the article, for instance (and in the era of deepfakes, it can even be imaginary.) That's why it's always important to learn who took the video/wrote the words/made the phone call, etc. and determine if that person is trustworthy (or even exists). If that information is hidden, then it's no better than hearing a stranger shout something on the street. They could be right, or they could be making it up. Not strong evidence.
If you want to provide a compelling factcheck, you have to explain what the video showed and what you can find out about the source of the video. Otherwise, it's just blind trust.
The burden of proof is always on the person claiming that something happened, as it's impossible to find evidence that something didn't happen. (For instance, try to prove that there isn't a unicorn floating by Pluto.)