So this video is trending on Facebook, and combined with the recent Gamergate mess, and some other things, there's something I need to make clear.
Trolling is the act of saying something to someone for the express purpose of getting a negative reaction. The something doesn't need any relation to the truth, or serve any other goal, just get a reaction. The bigger the reaction, the bigger the win.
And that's it. Success is rated by the degree of the outrage, and no other factor. Calling (in this case) a fitness instructor fat or criticizing her body is intentionally targeting the thing she takes pride in, not necessarily to make her feel bad, but to get a reaction. The goal in a case like this is to get the target to lash out and respond. That's it.
So, if someone responds to death threats by publicly announcing that they are leaving their house, that's a huge win for the person making the threat. The scale of the public reaction is enormous, and the outcry that follows constitutes an even bigger bonus. That's the largest scale version of someone joining a Taylor Swift forum for the express purpose of bashing Swift, and joining a gaming website to call the users nerds.
But the response doesn't have to be outrage and panic. It can simply be anger or public punishment. A long missive or rules change followed up by a ban from the website counts as a win just as much as someone breaking into public tears. It's the size, not the nature, of the reaction that counts, and to get it they will be as vile and outrageous as is necessary.
In that sense, the highly-produced, special-effect heavy video counts as a major victory for the people who mocked the instructor's looks. Launching a campaign that starts trending on Facebook is a great way to get attention - for the people who sparked the campaign in the first place. They're safely famous, in that they can brag about being "that asshole" while still almost completely anonymous.
The only real option in dealing with trolls is quietly denying them their goal. Ignoring them, and using social media ignore-functions, is the only option anyone has available to counter them. Flipping out, going after them, or launching social media campaigns confirms several things: 1) You're a choice target, 2) People are paying attention and 3) You have something new to mock to get new reactions. Ignoring them instead dries up the incentives for them to target you. Launching a major media campaign only guarantees more trolls.
Don't feed the trolls.