Probably hired through something like this anonomous ad and application through craigslist:
http://newyork.craigslist.org/wch/npo/5169192272.html
When you see those ads on craigslist, just click the ‘prohibited’ link at the top. If it gets clicked a few times from different computers, the ad will disappear. Craigslist is self-policed by the users.
So, we all just accept that these people organized themselves and showed up at Jeb's event. They were already organized and had some meetings to verify they all held similar political views. They discovered Jeb's event and decided to mount a protest. They arranged transportation to the event and it looks like they had their chants all ready.
These people are hired disruptors. Professionals made to look like real people. The question is, who is paying them? Soros? Hillary? Barack?
Hitler used to send the brownshirts to disrupt rallies of his opponents. The libs send the brown skins.