From viewing my swing on video several times now, its clear I am coming over the top with a reverse pivot.  From the vids I notice that I take the club away outside the line, its clear for all to see, and my left leg collapses on the backswing, with major head movement.

The question is - how the hell do I fix this ?

Take the club away more on the inside ? I've tried this before and it played hell with my swing. At first I was producng some great drives but after putting vids on here, comments back said it made my swing look awful, worse than before.  I simply cant carry on slicing OB - I had 5 x "3 off the tee" last week.

What works for me is the one piece takeaway. The early part of the swing is just a shoulder turn with no wrist break or lifting of the arms. Don't overdo it or you'll be too far inside the line. If you can rotate your upper body over your right leg, you should be able to do a full turn without your legs collasping.

Your video is no longer available, so I can't comment on your swing, but it would be wise to check your alignment and shoulder tilt(to the right). 

Dude the vid is here.....

By freezing the frame just before the club reaches horizontal, you can see that your arms are lifted but you've hardly turned your shoulders, hence the club has gone outside the line. Having said that, your top of backswing position looks quite good to me.

I think your main problem is with your downswing. You are coming over the top because your shoulders and hips are unwinding too quickly for the speed of you arms.

You could try starting the downswing by pulling the arms down as if you were bell ringing.

  If that doesn't work I think you need to change the way your legs work on the backswing so that they both resist the turn of the upper body. That way you'll be able to start the downswing with a weight shift rather than an immediate rotation.