How to accept manyToMany data from a form?

Question

Django

Hello, I can’t find the reason why data from many2many fields is not accepted, data is sent, but the form does not save exactly this field
Here is the form

class MovieEdit(forms.ModelForm):
    class Meta:
      model = Movie
      fields = ("actors", ...)

This is how I keep

class Movie(models.Model):
    actors = models.ManyToManyField(Actors, verbose_name=u'Выберите актеров')

And this is how I process

if request.method == "POST":
        movie = MovieEdit(request.POST, instance=movie)
        if form.is_valid():
            movie = form.save(commit=False)
            movie.owner = request.user
            movie.published_date = timezone.now()
            movie.save()
            return redirect('/my_movies/')

Tell me, what could be the reason?