The shot that went into the roof was while the truck was approaching the barricade, before he swerved into the snow bank on the left.
At 5:22 you hear the first shot hitting the cab and Finicum says "hang on" and then the girl says "they're shooting", followed by the sound of the second shot hitting the cab.
These officers who are all on the pavement and behind the vehicles realize that at his rate of speed he will not be able to stop.
The first two officers abandon their position and move into the snow bank on the right side of the road
By 5:25 the third officer is moving into the snow on the left side just as Finicum is swerving to the left. If the snow had not stopped the truck, the third officer would have been run over.
And Finicum said “you’ll have to shoot me” as he’s getting out of the truck and keeps repeating that until he does get shot.