The three had been killed in Hamas's attack on Israel on 7 October and their bodies taken to Gaza.
Seven others including four foreigners were injured, Afghan officials say.
The clip seems to show an attack described in Casandra Ventura's lawsuit against the rapper last year.
The warning comes one week after a similar alert from the FBI and Department of Homeland Security.
Nancy Pelosi has not discussed the attack with her husband, whose skull was fractured with a hammer.
It marks the opening of a new route for humanitarian aid to reach the stricken Gaza Strip.
The man was armed with a knife and a metallic tool and was shot by an officer after he threatened the police.
The protests which erupted on Monday have so far injured hundreds of people and killed five.
Nigeria's women's minister says she has filed a court order to stop the ceremony planned for next week.
The BBC's Jonathan Beale joins Ukrainian forces in Kharkiv as they try to shore up a weakened frontline.
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