Nasty looking, I too was bothered by the reactions of the other drivers and the pedestrians. However, there's too much not evident in the video to really answer "why".
Many gas stations are at intersections. This road looks to be a simple two lane without center turn lanes. If there's an intersection off the left side of the video, then its quite possible that another vehicle had been turning in the motorcycle's (i.e. "rightbound") lane and masked the visibility of both the car and the bike. The car figures he has plenty of time to clear because he can't see anything behind the XVan turning ahead of him. The motorcycle can't see far past the van, just knows he's got a green light and there's nobody turning in the intersection.
Mind you, this is simply speculation, and could be way off base. Or it could be dead on. Either way, it's certainly plausible. Which takes us to the next question: assuming for a moment that my scenario is accurate, what should the rider have done differently?
Before we get into it though, I want to remind everybody that yes, all motorcyle "accidents" / collisions are avoidable. Just take your motorcycle down to the scrap yard and have it crushed, voila, you'll never have another motorcycle collision. Now that the SafetyTrolls of La La Land have been fed, real world solutions that real world motorcyclists can implement.