The NFL is doubling down on its position that the Detroit Lions were to blame for the reporting fiasco that cost them the go-ahead two-point conversion in last week's 20-19 loss to the Dallas Cowboys.

The league sent a memo to teams Tuesday reiterating proper procedures for reporting as an eligible lineman. A video that accompanied the memo and shared by NFL Network included two clips of swing tackle Dan Skipper raising his arm as he ran on the field, presumably to alert referee Brad Allen of his intentions.

The video shows Skipper, who was circled in yellow in both clips, raising his left arm, then his right, as he ran towards Allen on a play with 12:50 left in the first quarter, when he checked in as an eligible receiver.

In the next clip, Skipper raises his left arm in the same manner as he runs towards Allen before the 2-point play with 23 seconds on the clock.

CARLOS MONARREZ: Dan Campbell has finally been Lionized but seems focused on one thing: Moving on

Allen appears to be looking in Skipper's direction as Taylor Decker and Penei Sewell approach from a different angle. Decker is wiping his chest as he approaches Allen, the universal indication he is reporting as eligible.

"To allow the defense an opportunity to match personnel to avoid deception and to ensure fairness, the player must immediately report the change in his eligibility status to the referee, who will inform the defensive team and will make an announcement to the stadium before that play," NFL senior vice president of officiating training Walt Anderson said in the video. "It is the responsibility of the player to be sure that change in status is clearly communicated to the referee by both a physical signal with his hands up and down in front of his chest and to report to the referee his intention to report as an eligible receiver."

Allen announced Skipper as an eligible receiver on the 2-point play, a tackle-eligible pass designed for Decker.

Decker caught the would-be 2-point conversion, but the play was nullified by an illegal touching penalty and the Lions failed on two more 2-point attempts in the controversial loss.

Skipper, in a brief interview after the game, said, "I did not say a word to the official" on the 2-point play, and Decker said he "did exactly what Coach told me to do and went to the ref, said report, and yeah, I don’t know."

DETROIT LIONS MAILBAG: Final thoughts on Lions' 2-point plays, Goff's contract and more

Allen said in a pool interview after the game Skipper "who had reported during the game a couple of times, reported to me as eligible."

On Monday, Lions coach Dan Campbell admitted the Lions were trying to confuse the Cowboys by sending three linemen in Allen's direction. Asked if Skipper wiped at his numbers to indicate he would be eligible on the play, Campbell said, "Not that I know of. Did you see something?"

"If you’re running a play like that and 70 (Skipper) is your jumbo tight end and they know that because that’s what he does for you, and then you’re going to decide you’re going to make 68 (Decker) eligible and he walks over to the ref and then the ref stands over 68 before the play and they hold the ball and they stand over and point at him, do you think you’re going to be able to throw the ball to 68?" Campbell said. "No, so it’s about eligibility, that’s what it’s about. And it has nothing to do with the ref. The ref knows. He knows, because 68 reported. It’s for the defense so that they see three different people and you’re just hoping they happen to not hear that it’s 70. That’s all."

Contact Dave Birkett at dbirkett@freepress.com. Follow him on Twitter @davebirkett.

This article originally appeared on Detroit Free Press: NFL is backing ref Brad Allen on Detroit Lions' botched 2-point play