Did you do it yourself.

I've been running into this a lot lately. For example, I'll try to discuss a well known, well documented experiment that was performed over 200 years ago and is performed by college students every year. I'll get push back with comments like:

"How do you know, you weren't there"
"If you didn't do it yourself, the your information is dismissed."

Similar replies to other arguments. I presented a video to illustrate a point and got replies like this:

"If you weren't there when the video was shot you don't know it's not CGI and since I wasn't there I can't verify it's not CGI so it's invalid as evidence of your claim"

These kinds of statements are used to dismiss even allowing evidence to support a claim. Does this fall into a particular fallacy category. I've hear some call this a genetic fallacy.

Seems like extreme skepticism or even denialism mixed with a lack of understanding of the scientific method. So no fallacy, just ignorance.

Yep. From what you say, your buddies aren't advanced enough to commit a fallacy. LOL.

I guess we could invent a new fallacy of "denialism." What do you think?

"How do you know, you weren't there"
"If you didn't do it yourself, your information is dismissed."

That's quite a self-defeating stance to take.

It's self-defeating because their own knowledge is often based on science or observations as well. Meaning that there is no reason to take their claims serious. They know nothing because everything they know should be looked at with the same skepticism because if true would apply to almost everything modern humans know.

It could be special pleading but most likely not a fallacy.

As Dr. Bo explains<>:

Special Pleading
Description: Applying standards, principles, and/or rules to other people or circumstances, while making oneself or certain circumstances exempt from the same critical criteria, without providing adequate justification. Special pleading is often a result of strong emotional beliefs that interfere with reason.

Example #1:

Yes, I do think that all drunk drivers should go to prison, but your honor, he is my son! He is a good boy who just made a mistake!

Explanation: The mother in this example has applied the rule that all drunk drivers should go to prison. However, due to her emotional attachment to her son, she is fallaciously reasoning that he should be exempt from this rule, because, “he is a good boy who just made a mistake”, which would hardly be considered adequate justification for exclusion from the rule.

You could reply with "Were you there to say it's not what happened?" It's extremely stupid but it highlights the issue with the line of reasoning.

You can also check the resources of who made the video, a CGI product that is visually indistinguishable from reality requires A LOT of resources. You would need a PC with a price tag of over 3000$ of just GTX 1080 graphics cards, completely ignoring processors, RAM and the sheer amount of space this sort of video would take up if you used CGI. And the price can only climb with how good said CG needs to be. Not to mention how much you would have to pay a professional, to make a near perfect work. My educated guess (optimistic) would be around 7K for the one PC alone, and then who knows how much the animator (or team, if the animation is that good) would cost. All in all, a huge number of resources are needed for this, it's not realistic depending on the company that made said video.

And I mean, the above goes for a really thought out plan for a company with only some thousands of money to spare. Pixar uses monstrous machines whose processor alone costs 4000$. Not counting the price of render farms, and the workplace, etc.
I'm confident that a simple video on an experiment would not have Pixar level CGI.