The video alleges, with subtitles, that while Mauer was on second base during Jason Kubel's at-bat in the sixth inning against Justin Verlander on Tuesday night, he was letting Kubel know which pitches were coming. The video suggested that Mauer was touching the ear flap of his helmet to signal curveball and the front of his face to signal fastball.
"It's a joke," Morneau said of the video. "It's funny, because you can look at anybody standing on second base and make a connection that if he's standing like this, he's giving pitches."
"That's why we're three games back -- we're stealing signs," manager Ron Gardenhire said before Thursday's 8-3 win over the Tigers. "We scored two runs last night; we stole a lot of signs."
Kubel wound up hitting a sacrifice fly in the at-bat to score a run. But if Mauer was giving him signs, Kubel said he was unaware.
"I certainly wasn't looking for anything," Kubel said. "That wasn't the way it was."
Mauer denied the accusations of the video, saying that touching the ear hole on his batting helmet is "just a habit of mine. I've always done it. I don't know why, but I do."
Throughout the visitros' clubhouse at Comerica Park, the Twins were watching the video on their computers and phones. It seems others were watching as well, since Mauer said he heard chants from the crowd during the game.
"I got out on the bases today and at first base, I heard, 'You cheater,'" said Mauer, who admitted he was a little more self-conscious about his gestures while on base. "And I'm like, 'Where is this coming from?' I don't know. It's just kind of funny."
"I wish I had the signs, especially with a guy like Verlander. You can use all the help you can get. But I didn't have them at that point."
While many players, including Mauer, got a chuckle out of the video, Kubel pointed out that some of the subtitles were incorrect on what pitches were being thrown.
"[The video said] a fastball or curveball, and it was a changeup," Kubel said. "Otherwise I would have hit it. I mean, if you look, Joe, even on first base, he's always touching his face and his ear, and he's doing it without looking at the catcher, too."
The Twins scoffed at the notion of Mauer tipping pitches, but Tigers catcher Gerald Laird, who was behind the plate in the video, told the Washington Post that the Twins have a reputation for stealing signs.
But after Thursday's game, Laird had watched the video and said he didn't see much evidence of it happening there.
"It didn't look like that big of a deal," Laird said. "We watched Kubel's at-bat ... and it didn't look like he was really on that many pitches. It was just one of the things that was said, and we took a look at it."
No one in the Twins' clubhouse denied that there are attempts by teams to steal signs, but Gardenhire seemed to find it funny that his team was being accused of actually being able to do it.
"That's the best they can come up with?" Gardenhire said. "Every team in baseball tries to steal signs. Every team in baseball tries to get the coaches' signs, the manager's signs, so ... really, that's old stuff."
Morneau added, "Guys do it, but Joe is not one of them, I know that."