TMZ Sports has obtained police footage of NFL star Junior Galette being run down by cops -- and then tased -- following an alleged fight in Mississippi back in April ... and the footage is insane.
It all went down on April 8 ... when a Biloxi PD officer saw the Redskins linebacker fighting with another man and instructed them both to freeze. The cop claims Galette ignored instructions and bolted.
You can see the cop -- who identifies himself as a "big white guy" -- sprinting after Galette while shouting, "Stop motherf*cker!