draw flash light on videos

Given a static video (Droite or Gauche) and the json file associated with it, 

This function visualizes the flash light on the whole video.

Input : 
   path_input_video (string) : path to the input video.
   json_file (json) : json_type_file containing the annotation of the video.



Output : 
processed video : flash_light visualized (using draw_bright_circle function of ntt).