code: def save(self, force_insert=False, force_update=False, using=None, update_fields=None):
          
          if self.url:
              iframe_html = '<iframe src="{}" frameborder="0" title="{}" allowfullscreen></iframe>'
              self.html = iframe_html.format(
                  self.get_embed_url(),
                  self.title
              )
          return super().save(force_insert, force_update, using, update_fields)
docs: Set html field with correct iframe.