It just dawned on me (duh) that Nazir may know that the video has been captured by the CIA. In which case it would make some sense to eliminate him. If Carrie and Saul can convince him that Nazir planned to have him killed he may turn on him. And they might actually sympathize with him if they find out why he turned, plus he hasn't actually killed any innocents. And as far as they know he just didn't go through with the bombing (instead of the reality that he pulled the trigger but it didn't work). I hope that's where the show is headed. The other, more contrived possibility is Saul will be killed, and the video destroyed before anyone else sees it, and of course no one will believe Carrie.
It's a certainty that Nazir knows the video was in the Beirut apartment, along with the materials that implicated the tailor. Of course Brody doesn't know that. What Nazir might choose to do about it is an open question and the writers can take that in any direction. I have to believe that Saul has adequately protected/backed-up the video so even if he's killed it won't matter.