The cop who busted Justin Blackmon for public intoxication earlier this month put a brief pause on arresting the ex-NFLer to educate him on some Oklahoma State football history ... police video shows.

Check out the body camera footage TMZ Sports obtained ... just after an Oklahoma State University Police Dept. officer stopped the former OSU Cowboy for allegedly roaming the Stillwater campus while drunk on April 19 at around 1:30 AM -- he talked a bit of ball with the one-time Jacksonville Jaguars wide receiver.

Blackmon stated he had played for the Pokes in 2011 -- and "went to the league" afterward. The cop then asked, "Did you play under [Mike] Gundy?"

Blackmon seemed confused by the question -- wondering who else he could've possibly played for. That's when the cop schooled him on Les Miles' brief OSU tenure.

The two talked about Gundy and Miles for a while as they waited for a bigger police vehicle to transport Blackmon to a nearby jail. Eventually, the football talk ceased once the car arrived.

Blackmon was largely cordial with the officer throughout their 15-or-so-minute encounter, though he did seem to be quite inebriated.

The 35-year-old -- who was wearing a hoodie and pants that looked to be wet -- slurred his words often, appeared unsteady on his feet ... and did not tell the officer what address he was heading to despite repeated questions.

Multiple times during their interaction, Blackmon insisted he hadn't done anything wrong ... which caused the cop to repeatedly tell him he was under arrest for public intoxication.

On his way to jail, Blackmon seemed to drift in and out of sleep while in the back of the squad car. He was ultimately booked on one criminal charge -- before he bonded out a short time later.