I know what person you're talking about. I saw him on a show touting his book, "Cures they don't want you to know about" or something to that effect.
He supposedly had this friend diagnosed with acid reflux. Given that prescription and what-not. So he told his friend to take one teaspon of vinegar, his friend took it and shortly after the burning went away. He didn't mention what KIND of vinegar though, did he? I don't remember if he told the guy white vinegar or ACV - --

Most "acid reflux" pain is actually TOO LITTLE stomach acid. If the pain hits immediately after eating, it is due to TOO LITTLE. If the pain hits 5 hours after eating, it is due to too much acid. Type O positive people tend to have too much. Everyone else, especially people over 35, tend to have too little. We manufacture less stomach acid as we age.

Apple cider vinegar has things that act as neutralizers/base in post-digestive effect, and things that act as acids/HCL in the stomach. It's amazing stuff! The pH is closer to the acid side than the alkaline side, and it has enzymes that help to break down proteins and fats. It is theorized that most stomach pain is due to undigested protein/fat which then adhere to the stomach lining and cause inflammation as the immune system comes in to attack.

I think I posted before that it was alkaline/neutralizer in the stomach, oops!