From the film it looks like he swerves to avoid the bike hitting the dashcam car, I assume the rider is further back on the ground, he may have never seen him down under the high dashboard, assuming that he thought he missed crashing into another crash scene. He is at most guilty of leaving the scene of an accident, if they can prove he ever thought he got in an accident to begin with, the bike never got hit by the lorry. Either way the biker caused this accident, and is responsible for his own predicament. I'm impressed at the swerving maneuver of the lorry, he probably saved him from getting killed.