code: def get_course_video_image_url(course_id, edx_video_id):
      
      try:
          video_image = CourseVideo.objects.select_related('video_image').get(
              course_id=course_id, video__edx_video_id=edx_video_id
          ).video_image
          return video_image.image_url()
      except ObjectDoesNotExist:
          return None
docs: Returns course video image url or None if no image found