The fireballs are the result of compressor stalls. With all the blades bent from the bird strike the airflow throught he engine is disrupted and caused the stalls. Stall - clear - stall - clear until it totally uncorks or it is shut down. What the video doesnt show is the fireball also going forward out of the intake. That really gets the passengers attention...especially at night. That is also why the seats are made or foam rubber....they are more easily removed.