This is a classic example of ad hominem argumentation.

That the Daily Mail is unreliable is certainly true, but this does not prevent it from carrying factual accounts of things. In this case, it seems to (somewhat uncharacteristically) provide direct support for its statements.

In rejecting the example, you're also moving the goalposts, which is another logical fallacy.

So your argumentation here is, as you say, "well beyond bullshit".

The poster did a decent if not spectacular job complying with your request--now do your part and make a decent counterargument (which could include that the report is fake, but you need to explain where the video came from if so).

Or just admit that you were apparently wrong.