Jeff B

Ah now it's beginning to make sense.  Thanks 

Thanks for this link.  I really need to get my head round it all and I think it is going to take some time! 

I have been playing around with making a person anonymous by pixelating the face.   I can do this on the first frame but I am unable to then follow the face in subsequent frames.  The pixelation stays in the same part of the frame it was originally placed.

Can anyone please tell me how I use the pixels to follow the subject.  

Thanks.

Jeff