See this guy in the above video running around like a mad man with Widowmaker? Odds are good that if you've ever been killed by someone like him then you've probably watched the kill cam, called foul and nearly threw your keyboard or controller right out the damn window. Well Blizzard wants you to take a step back and just accept that they're likely not cheating and simply better than you.
During the entirety of the beta phase various websites were used as sounding boards to post gifs, videos and clips of suspected cheaters possibly using aim bots and the like to exploit us honest, normal game playing folks. While Blizzard is encouraging all players to be on the lookout for rampant cheating by reporting suspect players to [email protected], they don't want their player base to take to publicly shaming every player that's able to do things like the guy in this video.
“Some players are just really good at first-person shooters. Through practice and years of experience, these players’ movements and reaction times can occasionally appear unnatural (if not physically impossible) to those who may not have been exposed to that particular level of play before."
That said, Blizzard is also claiming to take a huge stand against actual cheaters across the launch of Overwatch. They're threatening permanent bans to ANYONE found cheating even if it's their first offense. However, they also want to reiterate their first point about just how good certain players are. They don't want people depending on particular playback methods for proof.
“Our in-game camera system does not always play back footage at the same fidelity as real-time gameplay (this loss in fidelity applies to the killcam, Plays of the Game, Highlights, and—to a lesser extent—the spectator camera as well). This can sometimes result in a player’s aim appearing more snappy or less fluid in playback than it did in-game.”
Basically, a play that's completely legit and fair might look sketchy when spectated or viewed through the kill cam. Don't let that stop you from hunting down actual cheaters and helping to banish them with fair reporting. However, you should realize that the Widowmaker who dropped you and three other team mates with perfect headshots is likely just that good.