code: def convert_all_videos(app_label, model_name, object_pk):
      
      # get instance
      Model = apps.get_model(app_label=app_label, model_name=model_name)
      instance = Model.objects.get(pk=object_pk)
  
      # search for `VideoFields`
      fields = instance._meta.fields
      for field in fields:
          if isinstance(field, VideoField):
              if not getattr(instance, field.name):
                  # ignore empty fields
                  continue
  
              # trigger conversion
              fieldfile = getattr(instance, field.name)
              convert_video(fieldfile)
docs: Automatically converts all videos of a given instance.