I would presume a bit of verification if it were a YC funded startup, or really any identifiable company with funding. Not a lot, but some. Ties to a reputable institution like a university, or a person known in a field, etc. would also be positive.

If it's relatively anonymous, it has to stand on its own with whatever proof provided; I'd accept a claim from my neighbor-of-N-years that "your house is on fire" a lot more than I'd accept the same claim in email from Nigeria, but if someone had a live photo/video feed of my house on fire, I'd believe even an anonymous source to a reasonable degree (modulo photoshopping, etc.)