I THINK I'VE been living in Philly too long. Apparently, I don't know the difference between a hard sell and a shakedown.

The hard sell came at the hands of Rocco Martinez, 29, a likable amateur videographer who tried his best to sell me a video of a Philadelphia Parking Authority enforcement agent supposedly accepting a bootleg DVD in return for rescinding a parking ticket.

The shakedown allegedly came when Martinez tried just as hard to sell the same video to PPA Executive Director Vince Fenerty.

I turned Martinez down and went on my way. Fenerty, though, contacted the city inspector general and the FBI, which set up a sting. Last week, Martinez was indicted on extortion charges.

Which seems a little like shooting the messenger, but I'm getting ahead of the story.

Martinez covertly recorded the video last September inside the How U Doin' Deli, at 15th and Porter streets in South Philly. It shows a female PPA agent talking to a man who calls himself "the Movie Guy."

Background noise interferes with the audio, and the camera jumps around a lot. So you can't tell if the video depicts what Martinez says it does - the PPA officer rescinding a ticket that had been issued to the Movie Guy, in exchange for some bootleg DVDs.

The video does, though, show the Movie Guy doing a "whoo-hoo!" thing with his hands as the PPA woman taps something into her handheld ticket-writing unit.

The Movie Guy apparently then writes his name and phone number on a PPA envelope, gives it to the woman, promises to "be out of here in about five minutes" and then says, "Thank you, doll, I appreciate it, all right?"

(I called the Movie Guy - whose number has since been disconnected - but he wouldn't comment on the exchange. So who knows why he had been so appreciative?)

Martinez wanted to sell me the video. When I told him that the Daily News doesn't pay for such things, he said that a local TV station had offered him $1,000 for it, and that he'd been in touch with the PPA's Fenerty to gauge his financial willingness, too.

"This is the story of the century!" said Martinez, a character who made me laugh every time we spoke. "You don't want to get scooped, do you?"

For two days, he cajoled. I held my ground. Finally, exasperated, he gave me the DVD, gratis.

"F--- it," he said. "Just expose what this PPA lady did."

I wound up doing nothing. Without input from the Movie Guy or response from the PPA (which refused to comment), I couldn't confirm that a shady transaction had taken place.

Turns out the PPA didn't respond because Fenerty, who felt he was being extorted by Martinez, had contacted the city's inspector general and the FBI. They set up a sting and Martinez was himself caught on tape, allegedly telling Fenerty that the embarrassing video would be made public unless the PPA bought it.

"We didn't comment back then because we were working" with the feds, Fenerty said yesterday.

Fair enough. But what, I asked, did he think of the video's actual content?

"It was very cloudy and you couldn't make out the identity" of the PPA officer, Fenerty said. "I viewed the tape only once and then it went right to the FBI."

Actually, the PPA agent's face is very clear. And it would have been easy enough to check her handheld computer for the kind of activity Martinez says took place the day he recorded her inside the How U Doin' Deli.

Isn't the PPA at least a little curious about why the Movie Guy did the happy dance after his chat with her?

As for Martinez's private meeting with Fenerty, I've not heard the recorded conversation. Maybe Martinez got threatening. But honestly? I sort of doubt it.

Yes, I found him pushy (and a tad full of himself for someone whose video was kind of a mess). But he struck me more as a benign street guy than a wily extortionist.

And I'd still like to know what went down in the How U Doin'.

philly.com/Ronnie. Blog: philly.com/RonnieBlog. Twitter: @RonniePhilly.