As you may have gathered motorbikes are one of my passions in life. And as a change of pace I offer you this video.
I spend time observing riders for the Institute of Advanced Motorists, helping riders with advance skills for being safer and smoother on the road. One thing we talk about early on with people is the need for good rear observations, to make sure you look behind you (as well as in front and to the side), before you make any changes in your road position.
See the last few seconds of this video for what happens when you stop your motorbike for your mates video recorder and don't look behind you!