OpenCV with cutting video background.

This source code is a try to solve the video cutting background.
import cv2
from cv2 import *
import numpy as np
cap = cv2.VideoCapture("avi_test_001.avi")
while(True):
    ret, img = cap.read()
    mask = np.zeros(img.shape[:2],np.uint8)

    bgdModel = np.zeros((1,65),np.float64)
    fgdModel = np.zeros((1,65),np.float64)

    rect = (50,50,450,290)
    cv2.grabCut(img,mask,rect,bgdModel,fgdModel,5,cv2.GC_INIT_WITH_RECT)

    mask2 = np.where((mask==2)|(mask==0),0,1).astype('uint8')
    img = img*mask2[:,:,np.newaxis]
    cv2.imshow('frame',img)
    if 0xFF & cv2.waitKey(5) == 27:
        break
cap.release()
cv2.destroyAllWindows()