Afrin (عفرين) is a city in northwestern Syria managed by the district in Aleppo Governorate. The city is inhabited and controlled by Kurds.
The video depicts members of the People’s Protection Units, also known as the YPG (Kurdish militia), hauling dozens of corpses through the city on a flatbed of a semi truck. I don’t know who the dead are, but all the honking appears more celebratory, than grievance-struck, so my guess is these are people killed by the militias.
Props to Best Gore member @milalex for the video: