One popular video on the site shows a man being shot in the head. A stomach-churning series of photos shows another execution victim, his missing face a mangled mess of flesh.
More than 2,000 people died last year in a war between the Gulf Cartel from northeastern Mexico and traffickers based in the western state of Sinaloa. President Felipe Calderon has sent thousands of troops to several chaotic states to take on the drug gangs, who have decapitated police and killed soldiers.
The gangs, or their supporters, are now slugging it out online.
One chilling video on YouTube called "The Hit Men" shows a handcuffed man, apparently a Gulf Cartel henchman caught and beaten by police. He is curled on the ground and pleading with his captors. "They're going to kill me," he says.
Beneath the images, YouTube members boast in Spanish about the powers of rival capos Joaquin "El Chapo" Guzman, head of the Sinaloa-based gang, and arch-foe Osiel Cardenas, the Gulf Cartel's leader, recently extradited to the United States.
Several slideshows are backed by the pumping bass and blaring horns of a famous 'narco corrido' ballad called "To My Enemies," widely seen as a musical attack on the Gulf Cartel's private army, The Zetas.
The singer Valentin Elizalde was shot dead last year after reportedly performing the song at a concert in Gulf Cartel territory.
In one YouTube post, a user offers about $4,500 to anyone who can show proof of having killed members of The Zetas, "via photo, video or presenting the body."
A spokesman for Mexico's attorney general's office said on Monday that some of the people who abuse each other on YouTube seem to have insider knowledge of the drug gangs.
"The messages give the impression that members of organized crime are participating," Jose Luis Manjarrez said. "We can't rule out, but neither can we be totally sure, that this is being used as a form of communication by organized crime."
He said Mexican police are monitoring the pages.
A spokesperson for YouTube, which is owned by Internet search company Google, said the firm "does not allow videos showing dangerous or illegal acts."
However, videos on the site include the footage of a man being shot in the head in a murder attributed to The Zetas. It has been viewed more than 280,000 times.
The YouTube spokesperson said it was up to users to flag footage as inappropriate, and that all content so marked was then reviewed by the company and could be removed.
Despite Calderon's military clampdown, drug war killings have continued more or less unabated this year.
Last week, a group of men dressed as soldiers shot seven people dead in two brazen daylight attacks on police stations in the Pacific resort of Acapulco. The group was accompanied by two men who filmed the attacks, although the footage does not appear to have been posted on YouTube.