[Django]-Django reverse lookup foreignkey not working

You have specified related_name in your foreign key loopkup. so rating_set should not work now.

You can lookup like

ratings_of_video = vid_rate.video.all()

A better naming convention will be to use ratings in your related_name

class Rating(models.Model):
    video = models.ForeignKey('Video', related_name='ratings', null=True)

and then query like

ratings_of_video = vid_rate.ratings.all()