Ah I see, I forgot the topic of this specific comment thread. Political Leaders could also have similar problems though.

Example - Dictator A says terrible things on video/audio. Of course it's not going to be shown on their nations' broadcast website or in media.

How can the rest of the world make sure the video that was recorded is trustworthy?

The same way we did in the days of print media being the only media?

A network of trusted sources, reporters and newspapers that the public trusts. Eye witness accounts, a preponderance of evidence.

Basically it boils down to the reputation of the individuals involved in the chain of trust.

Personally I'm excited by the prospect that we might get mainstream investigative journalism back in some form.