Hi Joe,
Note that mouseover and mouseout only work on desktop and not mobile.
You can achieve this by adding a pause event on the timeline so the animation will not start when the ad loads:
At the first keyframe in the timeline Advanced mode, right click and select Add event.
Select Timeline > pause for action and page1 as the Receiver and click OK at the Configuration.
Then add the mouseover event:
Deselect all elements or click on an empty area on stage.
In the Events panel, click the Plus button.
Select page1 for target, Mouse > mouseover for event, Timeline > play for action, page1 for receiver and click OK at the Configuration.
Now add the mouseout event to pause the animation again.
Deselect all elements or click on an empty area on stage.
In the Events panel, click the Plus button.
Select page1 for target, Mouse > mouseout for event, Timeline > pause for action, page1 for receiver and click OK at the Configuration.
Attached is the test file so you can check out the events.
Hope it helps.
San
Google Web Designer team