If I make a wild-ass guess that the fireball was visible over a trajectory of about 100,000 feet, that's about 30 km.
At 11 km/s, then, it should appear for around 3 seconds.
I rewatched the video, which is 5 seconds in all, and it looks to me like the light is pretty close to three seconds long.
Aside from that, sure, it could've been slowed down, and could be at an angle, so it may all be a coincidence.
If I make a wild-ass guess that the fireball was visible over a trajectory of about 100,000 feet, that's about 30 km.
At 11 km/s, then, it should appear for around 3 seconds.
I rewatched the video, which is 5 seconds in all, and it looks to me like the light is pretty close to three seconds long.
Aside from that, sure, it could've been slowed down, and could be at an angle, so it may all be a coincidence.