Here it is ... a KEY piece of the video at the center of the Patriots SpyGate II scandal -- and it's reallllllly bad for the Pats.

The footage, obtained by "NFL on FOX" reporter Jay Glazer, shows the moments the Patriots video crew is confronted by Cincinnati Bengals' security last weekend over concerns the crew was illegally shooting video of their sidelines.

During the exchange, you can hear Bengals security express major concerns over the video -- since it REALLY looks like the videographer was SPYING!!

Remember, the Patriots say the video team was tasked to shoot a behind-the-scenes segment on an advanced scout for a show on the Pats website called "Do Your Job."

But, as the Bengals security official points out to the video crew, there's a large chunk of the video where you don't see the scout ... only the Bengals sidelines.

Here's an exchange from the video ...

Bengals Security: "And, this is a piece your filming on your advanced scout?

Pat's video crew: "Yeah."

Bengals Security: "Yeah? C'mon guys! I don't see the advanced scout in this footage!"

Patriots video crew: "No, that's not. We were trying to get some field perspective. That's my bad."

The Patriots crew offered to delete the video but the Bengals security told him, "The damage is done my friend!"

The Bengals immediately referred the matter to NFL security and the league has launched an investigation.

The Patriots have admitted the video team broke league rules -- but they insist the video team was NOT tasked to spy, claiming the whole thing was an accident.

For his part, Glazer says there WILL be a punishment -- but it's unclear what it will be at this point.

Bill Belichick has denied involvement -- claiming the video team does not report to him.

During the "NFL On FOX" pregame show on Sunday, both Michael Strahan and Curt Menefee expressed how BAD of a look it is on the team.

Especially since the Patriots were caught in a video cheating scandal back in 2007 and were punished heavily for it.