Were they doing the intentionally slow crosswalk shuffle thing, All but daring him to blow his horn and he did? Probably, imho.
For those not familiar with black on white racist tactics, this is a petty tactic that is rampant. Identify a white driver and then start to cross the street at a snails pace, never looking up. They'll do this with 50mph traffic. Funny that they are literally betting their lives that white people are too good to run them over.
Blacks are doing all they can to confirm every stereotype about them.