New footage of that insane brawl involving Philadelphia 76ers player Mike Scott and a bunch of Eagles fans shows the 6'8" baller throwing wild HAYMAKERS ... and the video is crystal clear.

31-year-old Scott -- a Virginia native and big-time Redskins fan -- got into an all-out brawl with Eagles fans Sunday before the game at Lincoln Financial Field in Philly.

It's still unclear exactly why the brawl broke out in the first place -- though there are rumblings it had to do with a coffin some Eagles fans had brought to the tailgate.

There's been speculation Scott thought the coffin was there to mock late Redskins star Sean Taylor, though that has NOT been confirmed.

The new footage is wild -- showing Scott throwing a ferocious overhand right at an Eagles fan ... followed by a 2nd haymaker that sends the guy flying to the ground.

A flock of Eagles fans give chase and close in on Scott while another man desperately tries to hold Scott back.

Eventually, things simmer down and everyone went their separate ways. Scott has not been arrested or charged with a crime. Neither were the other men involved.