There are some amazing scenes collected in the Frontline documentary “Egypt In Crisis,” which focuses on the aftermath of the popular uprising that toppled Hosni Mubarak from power—the June 2012 election that ended with Mohamed Morsi, the candidate of the Muslim Brotherhood’s Freedom And Justice Party, becoming the country’s first democratically elected leader, and the military coup that replaced him a little more than a year later. In October 2011, eight months after Mubarak left office, Christians took to the streets outside the offices of the state-run TV station to protest the government’s failure to protect the religious minority. Describing what happened next, Heba Morayef, of Human Rights Watch, says it was “a traumatic event for Christian minorities, for Christians in Egypt. It was the first time the military had used excessive force in that way.” It’s one thing to hear it, but her words are accompanied by ground-level footage of tanks tearing through the streets, plowing into (and plowing under) people, which greatly enhances the viewer’s appreciation of just how it might feel when the very forces that are supposed to be defending and protecting you and your fellow citizens decide instead to park a first cousin to a monster truck on your spine. “Egypt In Crisis” is something of a sequel to “The Brothers,” a segment that the reporter Charles M. Sennott worked on for the 2011 Frontline episode “Revolution In Cairo.” Sennott opens this film by noting that “Two and a half years ago, I came to Egypt and witnessed what we thought was a revolution.” Those words, rueful and sad, set a tone of mournful confusion. So do Sennott’s efforts to check in on Mohammed Abbas, a young member of the Muslim Brotherhood with whom he spoke back when the country first started coming apart. He’s seen in interview footage from 2011, and then, nine months later, he’s one of the candidates running for a seat in the post-Mubarak parliament.