I don’t have much backinfo here. The video seems to show the aftermath of a traffic accident involving a motorcycle. There is an injured boy on the side of the road with leg trauma that looks like possible amputation at the knee.
A more severely injured guy sits on the road. His left arms was ripped off at the shoulder, and a chunk of his lower leg is missing. Looks like he clipped something with that side of his body as he rode by.
Props to Best Gore member @african-angel for the video: