Rene van Leeuwen, who runs the irreverent Dutch video website Dumpert, told ABC News' Ian Pannell the now-famous video was first uploaded to his site on May 13 but was taken down shortly after upon request from police.
The video showed a person on crutches being beaten by another person, van Leeuwen said.
The video was tweeted by Jayda Fransen, deputy leader of Britain's far-right Britain First party on Tuesday with the false claim: "Muslim migrant beats up Dutch boy on crutches!"
Dutch police and prosecutors have confirmed to ABC News the video does not show a Muslim nor a migrant.
Fransen faces a charge of religious or racially aggravated harassment, according to police in Kent, England. She has been released on bail before a trial set to start on Jan. 29, police said. She pleaded not guilty.
Asked about the videos Wednesday, White House press secretary Sarah Sanders defended Trump, saying, "Whether it's a real video, the threat is real, and that is what the president is talking about. That's what the president is focused on, is dealing with those real threats, and those are real, no matter how you're looking at it."
"Obviously, if you’re against fake news like the president is saying he is, then you shouldn’t be retweeting fake news, which is obviously the case here," van Leeuwen said. "Sometimes reality beats anything you can make up yourself and I think that’s the case here."
ABC News’ James Longman contributed to this report.