Normally you leave them where they drop, but sometimes it's more dangerous not to move them.
A rider minding his own business is stopped at a red light. He notices a Yamaha R6 in cross traffic approaching very quickly. It tries to turn right but is going too fast, and instead falls over and hits the wall of the bridge hard. The rider instantly springs into action, trying to cross the intersection across his red light to help (illegal but justifiable in this case). By the time he arrives, the R6 is engulfed in flames. Normally you're not supposed to move a crash victim since they could suffer further injuries. But the burning bike is right next to him. What do you do?
In this situation, the fire is the greater, more immediate threat to the rider. Despite a fairly obvious leg injury, the rider and other good samaritans move the rider away from the bike and around the corner, out of range of the fire and any possible explosion. The helpers can be heard giving instructions to call 911. At the end of the video, just a minute after the crash, a siren can be heard, and an official-looking black pickup truck appears to be turning against traffic toward the crash.
Naturally, this post on Reddit led to a great deal of Monday morning quarterbacking over the incident. What did they do right, and wrong? One of the most important things I learned in my crash scene management class was to not move the victim. However, I also learned that if the danger to the victim is greater than the danger of causing further injuries by moving them, you move them. This situation absolutely qualifies. Exacerbating the leg injury, or the possibility of causing spine issues, from moving the victim is the lesser evil when compared the possibility of him burning alive next to his bike. Fire is one of the most clear-cut cases where you should move an injured victim to safety, despite the standard rule to the contrary.
You don't have to take my word for it. On Reddit, a registered nurse, a paramedic, and a combat medic all chimed in and confirmed that moving the victim was the right thing to do. Sure, they could have provided better support for his head and neck to minimize the chance of further spinal injuries, but an intact spine does you no good if you end up burning to death instead. For untrained civilians, they did the best they could and certainly helped save the victim's life. Yes, according to other comments about the incident, the rider survived. We wish him the very best for a quick recovery.