The subway train pulls into Times Square and it stalls there. It's not unusual: crime, crumbling infrastructure or the mentally ill stop the MTA in its tracks in New York City much more often these days.

Usually you just shrug and you wait. But yesterday was a little different. As we stood in the crowded train I noticed a group of teenagers pointing eagerly at someone on the platform.They couldn't contain their amusement so I looked out to see what was going on.

I saw a mentally ill African American man, about 60, in a cheap blue track suit, who was clearly in distress. He was homeless and although was standing in one place his entire body was convulsing, his arms flailing wildly, as though something was on him that he couldn't throw off.

It was pathetic and frightening. It never occurred to me that it could also be entertainment.

Because that's when I noticed the three teenagers had pulled out their smart phones and were recording the scene. One of them said: "Oh man, this belongs on Youtube." They were laughing uproariously. They sounded like it was the funniest thing they'd seen all day.

Now, it wouldn't be the first time the pain and distress of others got repackaged as entertainment. But surely there's a new level of callousness and utter disregard at work here. They weren't moved by his pain, they were amused by it.

That man was being literally consumed by madness and yet he was left to fend for himself on the city streets. On those streets his distress was compounded by the heartlessness of some of the citizens who had no pity for his plight. Instead of kindness, they showed him contempt.

I held up my iPhone and I pretended to film the three teens mocking the homeless man. When they became aware of it they got mightily offended. I pointed to them and then to the homeless man on the platform. Everything connects. I gave them a big smile. It probably wasn't the wisest thing to do but I felt it was time to do something.

This is the next generation of American citizens we're talking about - oh, not all of them, or even most of them, but enough of them. Presumably they'll vote too.

Attacks against the homeless are on the rise nationwide, and teenagers - even kids - are to blame. Of all the attacks against the homeless last year 64% were carried out by teenagers. Type "homeless" or "crazy homeless" into the search engine at Youtube and you'll find hundreds of homeless beating and baiting films like the one I was witnessing. It's an epidemic.

Everything connects. Yesterday it was a vulnerable homeless man being humiliated, tomorrow it will be someone else. If our youth haven't learned basic compassion by now they're not magically going to later.

These teenagers are part of the future of this nation. They regard the pain and distress of others as entertainment. You share the same streets with them.

Be careful out there.