BERLIN—A new documentary is shining light on Germany’s neo-Nazi music scene and the role it plays in cultivating a violent far-right subculture.

The film “Blut muss Fliessen” (Blood Must Flow) looks at the neo-Nazi music scene in Germany, as well as in Austria, Italy and Hungary. The documentary, which takes its name from a song adopted by Nazi storm-troopers, features footage from neo-Nazi parties and concerts taken by an undercover reporter.

It is a timely topic: Last week, German authorities slapped hate-crimes charges on a neo-Nazi musician behind the 2010 CD “Adolf Hitler Lives.” Singer Daniel Giese of the band Gigi the Brown City Musicians and the record’s producer were charged in connection with hate-filled lyrics claiming that no Jews died in Auschwitz and celebrating a spate of killings—known in Germany as the “kebab murders”—targeting small businessmen of Turkish origin.

The killings were the focus of a national day of mourning on Feb. 23, with a Berlin ceremony featuring an address by Chancellor Angela Merkel and a nationwide moment of silence. The murder spree, which took place between 2000 and 2007, claimed the lives of eight Turks, a Greek man and a policewoman. In November, German authorities discovered that the murders were carried out by members of an extreme right-wing group called the National Socialist Underground.

Many observers see a strong connection between neo-Nazi music and far-right violence in general. In its latest annual report, the German Office for the Protection of the Constitution called the far-right music scene an essential tool to bring in new recruits.

“The authorities really have to keep an eye on that scene,” said Peter Ohlendorf, the filmmaker behind the documentary, which had its world premiere here last week at the Berlin international Film Festival. “This kind of music is what we call an entree drug.”

The film’s undercover video was provided by a German reporter who goes by the pseudonym Thomas Kuban. Using a camera hidden in his shirt buttonhole, Kuban infiltrated neo-Nazi gatherings and gave his footage to news media. In a few cases, arrests were made as a result.

Much of the footage shows sweaty skinheads branded with swastika tattoos lounging around amid swirling smoke with sloshing beers. Skinheads are seen raising their arms in the banned Hitler salute and chanting, “Sharpen the long knives on the sidewalk, slide the knife into the Jewish body. Blood must flow … We s— on the freedom of this Jew republic.”

At a neo-Nazi shop in Wismar, in the former East German state of Mecklenburg-Western Pomerania, Kuban peruses CDs for sale by music groups with names such as Kristallnacht and Alcoholocaust.

The music is far from harmless, both Kuban and Ohlendorf stressed following the film’s premiere in Berlin. Kuban came to the screening wearing his signature yellow blazer, blond wig and glasses—a necessary disguise, he said, given the death threats he receives.

The neo-Nazi music scene cannot be dismissed as just a subculture, said Ulli Lentsch of the Berlin-based anti-fascist Press Archive.

“Its protagonists … work in national and international networks,” Lentsch said. “They nurture contacts with those who share their views, and they earn money—for themselves and the Nazi movement.”

News about far-right concerts, most of which take place in what was formerly East Germany, often spreads via text messages. Kuban himself had to pass several checkpoints before actually receiving a ticket to a concert. At the first checkpoint he was given the once-over and sent to the next station. He pretended to be paranoid about being followed by cops.

But according to the documentary, the authorities hardly ever seem to be much of a problem. At one party, Austrian police chat with neo-Nazis and leave before the illegal music begins.

In the former East German town of Mucka, in Saxony, a local politician from the extreme-right National Democratic Party is seen hobnobbing with partygoers. Later the club owner apologizes to disappointed skinheads that because of complaints about illegal music, they will have to switch to a benign form of entertainment. The next scene shows a conga line of neo-Nazis dancing to German folk-pop music.

It’s a comic interlude in a sea of hate.

“These are not birthday parties,” said historian Michael Kohlstruck of Berlin’s Center for Research on Anti-Semitism, who specializes in youth culture. “Terrorists come from these kinds of circles.”

Kohlstruck said that such gatherings should be prevented from taking place.

“There are people who cannot get out of this scene,” he said.. “If there is no contact from the outside, they seal themselves off into their own world, where everything is blamed on foreigners and Jews.”