Uh, you don't know how the law works do you in most places?
Just because there is a homicide doesn't meant charges are always filed. There is police investigation. The police find any evidence they can of any possible criminal activity related to a homicide. Anything they find, and don't find is presented to the DA's office. The DA's office decides based upon the investigation to file charges of criminal conduct by any party involved. If there isn't evidence to support a manslaughter charge found by the police investigation then there won't be any charges brought by the prosecution, usually. Although technically the prosecution can still file for criminal charges even with no evidence, it won't go very far in court though without any supporting evidence found by police investigation.
Uh, don't know why you're copping such a dipshit tone, but yes I am aware of how it is, and based on the evidence so far (which is more than just the video by the way), it seems that minimum they should bring manslaughter charge. They very well might not claiming they wouldn't have enough evidence to make a case.
But by all means explain to me exactly how things work. You left out all the exact forensic science they'd utilize.
When I watch the video in slow motion on youtube, it is clear that Tony's car does not swerve or move off his line until impact with Ward was made. The swerve is the result of the tires driving over uneven surfaces. In this case, 3 tires are connected with the road, and the fourth tire is connected with Ward's body. That will cause the swerve seen in the video. The video also shows that no new acceleration was made by Tony's car in that turn either as the distance per frame the vehicle travels does not increase. Lack of distance traveled = no acceleration prior to impact.
The engine "gunning" noise people supposedly hear could be from any other vehicle on the track. Most likely from a closer vehicle to the camera man and not Tony's car on the far side of the turn away from the camera man. It could have been the engine of the safety crew trying desperately to get to Ward to stop him in order to save him from himself. Considering the safety crew is coming from where the camera man sits, this is the most likely possibility for the increased engine noise.
I do not see any indication when I watch the video frame by frame of any action taken by Tony that could be seen as anything that would have resulted in this tragedy. He neither sped up, not throttled the engine when next to Ward. Ward can me seen as coming clearly into the line of his vehicle on the track.
Now my time to act like a dipshit. Ya see, the thing is, they have this stuff called eyewitness reports (you know when police are investigating, they sometimes like to ask people that were there what happened). I believe they have people saying that Stewart gunned the engine there.
The video doesn't provide enough to say how things went exactly since his car appears onscreen just after the engine revving noise, which looks to me that he accelerated just before the car is onscreen in that clip. You should notice how much his car moves up the track as he struck him, which generally is a sign that the car was steered there. Its a drastic move and is not just from the change in drive from when his tire struck the guy. Watch the video again, at the start Tony's car is fairly low down on the track (bottom half easily) but within a very short length its up almost as high as the guy's wrecked car is, partly because hitting the guy caused the car to shift, but it was already moving up the track, which definitely looks like he was steering at the guy (considering the wrecked car was also up there, which he'd be steering away from). Actually just the fact that the car immediately pitched the way it did indicates to me he was steering it right, as if he was steering away from the guy the car would have smeared him even more, or would have oversteered in the opposite direction once he hit him). As for the sound, it sounds like a quick stab of the throttle. The sound is definitely not emergency personnel, that is how those (sprint) cars sound under throttle. Plus its a quick stab of throttle, which the emergency vehicle you'd hear a sustained sound of the engine as it roared down the track.
The other thing, and again we can't tell from the video but I'd be curious what Stewart's reaction was. He had to know he hit the guy. My first reaction to hitting someone, regardless of it being on a racetrack or on a normal road, would be to pull over and stop ASAP. Maybe he did, or maybe he wanted to be out of the way of emergency responders, so it might not be a big deal.
Another driver that was there said he saw the guy clearly so I don't buy the visibility aspect unless Stewart wasn't paying attention (in which case he should not be on a track).