The footage, posted by French journalist Philippe Buffon on YouTube this week, appeared to show Bosnian Serb fighters hiding in a house in the suburbs of Sarajevo.
One of them could be seen firing a sniper’s rifle and boasting that he hit someone “in the head.”
Bosnia-Herzegovina’s prosecutor’s office said in a statement that a case was opened “immediately” after the video appeared on the Internet.
The office said its Special Department for War Crimes will examine “all the circumstances and the role of all the people in the recording.”
The local telecommunications company Telemach BH said it had contacted prosecutors after one of its employees was recognized in the video. It said the employee had been suspended.
The YouTube video, titled The Snipers Of Nedzarici, after a Sarajevo neighborhood, was no longer available on the video-sharing platform on May 21.
The footage was distributed on social networks and broadcast on local television, causing a stir in the Bosnian capital, where more than 11,000 people were killed in the siege by Bosnian Serb forces.
Separately on May 21, Bosnia’s top court indicted eight Serb ex-soldiers on charges of crimes against humanity for their alleged involvement in the killing of 78 Bosnian Muslim civilians during the 1992-95 war.
Prosecutors accuse the former soldiers of “persecuting the Bosniak civilian population based on national, ethnic, and religious grounds with discriminatory intention, and of killing civilians in violation of the international law.”
They say the eight Bosnian Serbs had driven Bosniak civilians out of a school in the western village of Velagici, lined them up, and shot dead at least 78 people in June 1992.
There were no comments from the suspects or their representatives. Some are now believed to be in Serbia.
Hundreds of people have been convicted of crimes committed during the Bosnian War in which more than 100,000 people were killed.
Local judiciary officials are still examining some 600 cases involving 4,500 suspects, according to official data.
The conflict ended in a U.S.-brokered peace agreement in 1995 that divided Bosnia into two entities — the Muslim and Croat federation and Republika Srpska — held together by joint central institutions.