I believe you are right, that the Taliban does not commit acts like this. It does however commit other acts that are also shocking to many and are not praiseworthy. Neither side seems to be very exemplary in this conflict.
On another note, I was listening to a interview of a retired colonel discuss this incident, and he said that he believed that the mindset demonstrated in this video, the complete disregard for human dignity and honor, is traceable all the way back to President Bush and his administrations (you are not allowed to post links yet)"you can't post links until you reach 50 posts_en.wikipedia(contact admin if its a beneficial link)/wiki/Unlawful_combatant#2001_Presidential_military_orde"]practiced dismissal of the Geneva conventions[/url]:
All members of the U.S. Armed services are required to have training on the Geneva Conventions and Law of War at basic training. This training reoccurs on an annual basis.
It is true the Bush administration at the highest levels did order unjust things which went against those conventions, and I can see how theoretically, this could be an influence. Still, at every lower level, members of the armed forces are trained about these laws and are warned of what articles of the Uniform Code of Military Justice they violate and what the probably punishment will be. You can guarantee these members will be punished.