As I noted on my Elite audio Hotline last night, the word making the rounds backstage was that a number of fans had shoved and taken shots at Punk as he reacted to being told he would have to choose Ryback or John Cena as his Hell in A Cell opponent. Punk finally defended himself as there was no security around him.
In a cell phone video taken by a fan right who was right in front of the incident, that version is backed up. In the footage, a number of fans reach out to touch Punk as he runs up the stairs. When he stops, he is shoved and jostled several times, including by a fan he shoves away to his left.
Punk is shoved forward from behind, with the fan in question coming into contact with Punk. It appears that fan, wearing a black shirt and glasses, has been shoved from behind.
The fan raises his arms in the air and brings them down, hitting Punk in the back of the head. That leads to Punk physically nailing a backfist and another punch, defending himself.
Whether the fan meant to strike Punk or not, it's obvious from the footage that Punk believed that fan had struck him twice from behind.
The video also kills the silly rumor that the fan was actually a planted WWE developmental talent.
Updated: 12:25 PM.
Tomer sent along a high definition cleaned up version of the Punk fan video and it's obvious from that version that the person responsible for the entire incident was a second fan wearing a white t-shirt. He shoved the fan with the black shirt into Punk and then reached around to slap Punk, setting up the chain of events where Punk drilled the fan in black with a backhanded fist and another shot. If anyone should be held responsible, it's the fan in white.
This video allows a close-up look of the fan responsible:
Thanks to everyone who sent along videos.