Craig, thank you very much indeed for your reply, I really appreciate it.
Thank you too for spotting the vital flaw in my email- stress will do this to a man!
The videos are for a ‘start up’ app, and the client is concerned about the amount of server space 50, 3.5 gig videos will use, as well as stream and download costs- hence wanting them as small as possible to try and keep the costs down.
I already compress my videos for YouTube and Vimeo, but thank you for the pointers, as well as the really useful maths, and I shall further investigate.
All the best,
Ben