MONTREAL - A less-than-flattering ad of Parti Quebecois Leader Pauline Marois, with a possible election approaching, has prompted a threatening legal letter.

The ad contains images of the opposition leader during a recent protest banging on pots, and casting a quizzical gaze at them.

The man who originally shot the video, and posted it on Facebook, is upset it's now being used by the governing Liberals in a political ad and has sent a letter demanding it be taken down.

In their response Tuesday, the Liberals emphatically refused to withdraw the ad.

Premier Jean Charest defended the 15-second spot, which doesn't contain a single word. All it does is show the PQ leader marching, banging pot covers together, and staring at those makeshift cymbals. The images are shown in black and white and slowed down for dramatic effect.

"This illustrates an episode in the political life of Pauline Marois that Quebecers have an interest in knowing," Charest told reporters Tuesday.

"The image speaks for itself. We did not suggest a conclusion Quebecers should reach — given how obvious that conclusion is."

Marois spent the spring encouraging student protesters, even wearing their iconic red square on her lapel. Now, with an election approaching and polls suggesting the protests might have limited support, Marois has stopped wearing that red square.

A provincial election could be held as early as September, with a campaign beginning in August. Charest, however, has more than a year before he needs to call a vote.

A McGill University expert on intellectual property and Internet suggested the Liberals might be forced to stop running the ad because it goes against the creator's moral rights under the Copyright Act.

Richard Gold said that Facebook is normally a grey area because certain uses are permitted when it comes to images, such as sharing a video with friends or commenting on it.

"But this is quite different," he said. "This is taking it off Facebook and associating it with a cause."

Gold said he doesn't believe the Liberals have the right to use the video for their own purposes without permission, nor do they have the right to manipulate the footage.

He said this ad is different from a famous one made by the federal Conservatives. The notorious Stephane Dion, "not-a-leader," ad used media footage from a 2006 leadership debate in which Dion responded to criticism from then-opponent Michael Ignatieff by saying, "Do you think it's easy to make priorities?" The spot painted Dion as weak and indecisive.

Comparing this Marois ad to that one, Gold said regulated broadcasters generally make their footage available, while Seguin as a private citizen has no obligation to do so.

He said, however, that if the PQ had obtained rights to the video or if it was shot at their behest, then the Liberals might have an opening to argue that it's fair game.

That's exactly what the Liberals argued Tuesday in a note to the video poster, Guy Seguin. The reply was somewhat tongue-in-cheek.

"You will understand our surprise at your claim today that you do not consent to having these images reproduced or used for political purposes," said the letter from Karl Blackburn, the Quebec Liberals' director general.

"The images in question were obtained on the Facebook page of the Parti Quebecois candidate in the Argenteuil riding, Roland Richer," he said, referring to the PQ candidate who recently won a byelection.

"This candidate spread them for political and partisan purposes, without any reservations and with the explicit or implicit consent of the person who filmed them...

"Furthermore, in consulting your Facebook page, 'Let's dump the Liberals,' which uses our own logo, I noticed that you also used a parody of an ad we paid for and authorized. So it seems evident to us that you understand very well the political context."

-With files by Alexandre Robillard and Andy Blatchford

Earlier on HuffPost:

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  • Police Police use pepper spray and fight with protesters during an arrest on St. Catharines street near the Montreal Grand Prix festival area Sunday, June 10, 2012, THE CANADIAN PRESS/Peter McCabe

  • Police remove a person after holding him for 15 minutes after a brief confrontation in the Berri UQAM station early Sunday, June 10, 2012. Protesters declared they would disrupt the yellow subway line to the Montreal Grand Prix. THE CANADIAN PRESS/Peter McCabe

  • A Police officer searches an F1 fan at a metro station close to the venue of the Canadian Grand Prix in Montreal, Sunday, June 10, 2012. THE CANADIAN PRESS/Graham Hughes

  • Police officers question a woman wearing a red square, the student protest symbol, at a metro station close to the venue of the Canadian Grand Prix in Montreal, Sunday, June 10, 2012. THE CANADIAN PRESS/Graham Hughes

  • Demonstrators hold a sign displaying concern about sexual exploitation during a march protesting the Canadian Grand Prix auto race in Montreal, Saturday, June 9, 2012. (AP Photo/The Canadian Press, Peter McCabe)

  • A line of Quebec riot police keep protesters away from Old Montreal on Saturday, June 9, 2012. (AP Photo/The Canadian Press, Peter McCabe)

  • A policeman guides away a protester attempting to enter the Canadian Grand Prix auto race festival area in Montreal on Saturday, June 9, 2012. (AP Photo/The Canadian Press, Peter McCabe)

  • Protesters advance heckle police trying to keep away from the Canadian Grand Prix auto race festival area in Montreal on Saturday, June 9, 2012. (AP Photo/The Canadian Press, Peter McCabe)

  • A vandalized police cars is parked at the corner of Crescent Street and St. Catherine Street in Montreal after a conflict with protesters near the Canadian Grand Prix auto race festival site Saturday, June 9, 2012. (AP Photo/The Canadian Press, Peter McCabe)