It's more complex than that because not every black person is equally likely to have an encounter with the police. There are studies that suggest that if you control for encounters with the police, blacks are just as likely as whites to be killed by the police. Half of violent crimes in the US are also committed by blacks. This is definitely one of the consequences of the history of slavery and segregation. Nevertheless, given that blacks commit 50% of violent crimes, it should be expected that the percentage of people killed by the police who are black, will be higher than their rate of representation in the general population.

There ARE also videos of whites getting killed in conditions just as tragic as e.g. George Floyd, Breonna Taylor, etc. But they go largely unreported in comparison.