Как добавить водяной знак к видеофайлу при сохранении в django

Я могу добавить водяной знак на видео, но как это применить к django модели.

model.py

class Video(models.Model):
    title = models.CharField(max_length=100)
    slug = AutoSlugField(populate_from='title')
    photo = models.ImageField(upload_to='photo/%Y/%m/%d')
    video_uploaded = models.FileField(upload_to='video/%Y/%m/%d',blank=True,null=True)

views.py

def add_video(request):
    if request.method == "POST":
        form = VideoUploaderForm(
            data=request.POST,
            files=request.FILES,
        )
        if form.is_valid():
            obj = form.save(commit=False)
            vid = request.FILES['video_uploaded']
            clip = VideoFileClip(vid.temporary_file_path())
            # watermark
            video = VideoFileClip(clip.filename)
            logo = (ImageClip('faiklogo.png')
                    .set_duration(video.duration)
                    .resize(height=50)
                    .margin(right=8, top=8, opacity=0)
                    .set_pos(("center", "bottom")))
            final_ = CompositeVideoClip([video, logo])
            final_.write_videofile('videwithwatermark.mp4')
            obj.save()
    else:
        form=VideoUploaderForm()
    return render(request, 'firstapp/add_video.html', {"foenter code hererm": form})

form.py

class VideoUploaderForm(forms.ModelForm):
    class Meta:
        model = Video
        fields = '__all__'