Sounds fun. Could you attach the ad again (possibly there is a delay/no attachment yet). Also - do you have the .fla available to look at? (you mentioned Flex and Flash below)
I would probably plan to build 2 separate ads. One Flash and one HTML5 (I have heard that sometimes Swiffy works and sometimes there are issues). In other words, lets build the Flash version first, export with swiffy and if there are unsolvable issues, I can build out the HTML5 version following the specs you linked too.
What is your deadline?
Look forward to finding out more.
Regards,
Jeremy