Some of Mr. Hermansson’s most arresting footage comes from a June meeting with Jason Reza Jorjani, a founder, along with the American white nationalist Richard Spencer and others, of the AltRight Corporation, an organization established to foster cooperation and coordination among alt-right groups in Europe and North America.

Mr. Hermansson and Mr. Jorjani met at an Irish pub near the Empire State Building, where the baby-faced Mr. Jorjani imagined a near future in which, thanks to liberal complacency over the migration crisis, Europe re-embraces fascism: “We will have a Europe, in 2050, where the bank notes have Adolf Hitler, Napoleon Bonaparte, Alexander the Great. And Hitler will be seen like that: like Napoleon, like Alexander, not like some weird monster who is unique in his own category — no, he is just going to be seen as a great European leader.”

More shockingly, Mr. Jorjani bragged about his contacts in the American government. “We had connections in the Trump administration — we were going to do things!” he said at one point. “I had contacts with the Trump administration,” he said at another.