The problem takes place when I'm roughly at 5:20mins of the tutorial.
When I try and create the sculpt deformer, I create it but I don't end up with the result that the tutorial does and when I try and move my locator to where it should be after by setting all the channel box options to 0 it doesn't go where it should.
Instead I'm faced with the following warning when I create the sculpt deformer.
'Warning: Cycle on 'BicepShape.local' may not evaluate as expected. (Use 'cycleCheck -e off' to disable this warning.)'
When I ignored this the first time just to check whether it was causing a big problem I got to the part where you set the driven key ect. and when I scroll through the animation the deformation of the bicep just jitters about.
Here is an image of my outliner, deformation result and the warning.