Several weird things here that initially led me to believe it was an internal reflection, but other things tell me that’s less likely.
1) At 5.7s the streak splits into 2 parallel streaks for a single frame, not a motion-blur stretching (as seen 2s later), but 2 clear separate streaks. That seemed like an optical aberration of some sort, such as some additional reflection were the thing filmed behind glass (thus possibly putting the cause of the streak in the room with the filmer).
2) The glare at 9.5s is fairly extreme ... Read even more
