I don't believe those commercials are paid for by MTV are they? They sound like those AdCounsel PSAs that run on most channels. My guess is that they frequent MTV's airtime because of the audience (doesn't do much good to run them during All My Children or Barney & Friends

)
And no, this is not new info. These are highly distorted 'facts' in order to prove a pathetically losing point. The commercials fail to make any connection that marijuana actually causes the accidents - just that it so happens to be in some people's systems at the time of the accident. Heck, those commercials don't even say if the person with pot in their system was the cause of or the victim in the accident. Completely vague.
I betcha if you tested them to see if they've eaten fatty foods in the last month, that test would come up positive too. Doesn't mean eating Mickey D's causes accidents.
These commercials remind me of the Reefer Madness propaganda that was spewed in the 1920's & 30's. It's a load of lies. When our government is willing to lie to us, we start to lose trust. This is a very poor public relations move. Most people can see right through the bull.