Well aside from the fact that the video in question shows 95% South Florida blacks, per capita Africa Americans in the United States are in far more physical fights than any other ethnicity.
If I had to argue about that, I'd argue that it has way more to do with poor education and low income than race. The fact that illicit violent sport seems to be recurrent in low class communities all over the world suggests its not a black thing. Its unfortunate that this community of low income people all happen to be black, but its their circumstance not their ancestry that has them venting their energies in this very irresponsible way.
You've got backroom MuayThai in Thailand, field Escrima matches in the Philippines, Random restoraunts offering MMA with dinner in Hong-Kong, 50+ person gang-brawls in eastern Europe, Back road bare knuckle fights in Ireland.... Hell, even middle schools are hosting secretive fight clubs in the bathrooms today. The origin of Brazilian Jiujitsu was in Vale Tudo fights in brazil. What was orignally fights for dollars in a hat evolved into exhibition matches against any opponents, and finally into an empire and martial art that swarmed the world... But its roots, are planted in the Barra's of rio.
This has NOTHING to do with race, and everything to do with income and access to proper outlets for these kinds of physical impulses. Even one of the fighter fondly recollected over his collection of boxing trophies; if he had the option to go back to his glory days I'm sure he'd jump at it. The sad fact is though, that these people can't afford to go take brazillian jiujitsu at a gracie acadamy, or study muay thai in NYC, or do collegiate wrestling, so they turn to this in the backyards.
White, Black, Asian, Latino, European, African; it don't matter. There are groups of people who have a mild interest in combative sports in all ethnicities. The poor rungs of society can't afford a place that charges 100+ dollars a month to do it is all.
The stat you mentioned would probably evaporate completely if you accounted for collegiate wrestling matches, boxing matches, Sparring in judo/bjj/karate/tdk... Id put money on rich white people DEMOLISHING black poor people in how many fights they 'get in'. The difference though, is that those rich white people can afford to have their fights in a place with mats, medics, coaches and insurance.