If you use Pinnacle Studio

1. Download and install Pinnacle Studio
2. Download and install Adobe Photoshop
3. Open Video In Pinnacle
3. Take a snap shot of video in JPEG format
4. Open JPEG in photohop
5. Block face with any thing you wan circle object square or even a hello kitty picture
6. Make video picture not visible leaving behind just the object used to block the face.
7. Create a PNG file.
8. Drag and Drop that into Pinnacle.

(NOW THE LONG PART DEPENDING ON HOW MUCH THE FACE MOVES AROUND)

double click on PNG and click edit from start to finish.
now with this feature you can zoom and move the object all over the video to block the face in a smooth motion.