Looked at your site, some inspiring work there Simon. And you get to drive some nice cars! Great.

Given that you've lots of strong shots, I'd let that drive things - no sense in over complicating things. Start at the end and deconstruct - show a portfolio you came up with for a client then show how you built up those images, location slection, style etc but concentrating on the non-obvious tricks of the trade or the techniques unique to automotive/advertising market. Thats what I'd be interested in anyway. Keep it fast paced.... mmm... seems like you'll need to do several short videos to cover it all...