In simple terms, Jammy. If something is not proven, then it is not a fact, merely an opinion.
For example, if you were to bring criminal charges against them, would the prosecution use your 'opinion' as the basis of their case?
If I were of the opinion that you had committed XYZ offence and the Police charged you based on my 'opinion' and no evidence, would you consider it fair or reasonable? I think not.
It is really simple, you can not make accusations stick based on un-proven claims. Falsifying that youtube video has not made me think much of either side- BOTH sides have OBVIOUS forgeries... But then again, they are targetting young minds who don't have the benefit of being able to see through lies.