May be this one where Bezos speaks about Animoto at Startup School 2008: https://www.youtube-nocookie.com/embed/uIc-VB-ke9o

Here's the full talk (which was titled, AWS: We make electricity, so you don't have to): https://www.youtube-nocookie.com/embed/6nKfFHuouzA

ahh brilliant! I was just linking off to https://aws.amazon.com/blogs/aws/we_build_muck_s/ which is Jeff Barr's recap of Bezos' pitch at the time