Brief: Low file size, 15 seconds, and updatable.
Usually each creative concept would inlcude 300x250, 728x90, 468x60, 120x600, 160x600, and 970x250 sizes. As such they are action script driven (as opposed to timeline) and fast to update.
Often the campaigns would include YouTube banners and mobile executions - either gifs or HTML5 Celtra banners.
As the campaigns were being produced by so many designers, it was clear that the libraries and timeline be as clean as possible so that the 'next guy' could hit the ground running. Greensock tweening classes power the animations.
300x250 - Credit cards
300x250 - Step bonds