NFL's Willie McGinest -- Ringside Seat ... In Viral Bully Beatdown Video

Interesting cameo in that viral video of the bully who was forced to get into a boxing ring after picking on kids at school -- ex-NFL star Willie McGinest was there egging on the action.

The video has roughly 3 MILLION views ... and the family has been praised for teaching the kid an impactful lesson in humility after learning he had picked on a fellow classmate.

But we noticed that while the kid was getting his face blown up by more experienced boxers at the Jack Rabbit Fitness gym in Long Beach, Willie was there ... taking part in the tough love.

You can hear Willie shouting at the kid, "C'mon tough guy!" over and over ... while recording the beatdown on his phone.

FYI -- we're told the kid has trained at the gym before ... and the boxers he was fighting weren't pros, just more experienced. His family wanted to show him that being picked on by someone who's bigger and stronger sucks.

By the way, lesson learned.

We're told Willie insists he just happened to be in the gym that day ... and had no role in organizing the event.