Working on Ben's excellent idea I have thrown together a quick (30 sec) video cobbled from bits of my 2 days commuting with a camera (I know, such a huge resource of film to work with!!)...
One thing I have to say is that it's damned difficult to work within 30 seconds!!
The Bus needs to be replaced by some relevant HGV footage, and the other stuff doesn't accurately reflect the ideas Ben suggested (left hand lane with traffic on right, right hand lane with traffic on left etc.) but it gives an idea of how it might work/look and some clue as to how easy or hard it may be to get the 'correct' footage.
I find it easier to work with something 'real' rather than paper with words.
So, may I present a "3C Group" (Cycle Chat Campaigners Group) draft production of the HGV Awareness/Undertake -> Undertakers/"Be patient, not a patient" message.
Here.