The video from inside Ralph Wilson Stadium will help prove that Robert Hopkins, 29, ignored the risk he could hurt other people during the Nov. 17 game against the New York Jets, Prosecutor G. Michael Drmacich told a six-person town court jury.
Hopkins could face a year in jail if convicted of the misdemeanour counts.
Defence attorney Patrick Brown called it an accident that legally did not rise to the level of a crime.
"It's going to turn on, was this conduct reckless?" Brown said during his opening statement to jurors. "There's a technical definition of reckless."
As other fans in the stadium's top tier told him to stop, Hopkins repeatedly slid in a seated position down the rail, climbing over empty 300-level seats to do it again, Drmacich said.
The fifth time was "when it all goes wrong," he said, describing video, which he said is different than grainy video widely circulated online soon after the fall.
"The defendant loses his balance, his feet go up over the top of him and he flips over backwards. He hangs on. ... Now he's dangling, and he can only hold on for a second and he loses his grip and falls about 25 feet into the crowd below," he said.
Mark Bratcher, the 29-year-old social studies teacher Hopkins landed on, didn't immediately comprehend what had caused the "crushing pressure" as he watched the game from the 200-level seats, Drmacich said.
"It came out of the blue, literally. It came falling out of the sky," the prosecutor said.
Bratcher will testify about spinal injuries that require regular sessions with a physical therapist and chiropractor, Drmacich said. He has filed a civil lawsuit.
The trial is expected to conclude Tuesday.