Keynote on iPad - How can I pause a video in a presentation?

What's the best way to be able to pause an MP4 video within a keynote presentation for iPad?

I don't have a full version of keynote for my mac yet - I thought about trying to insert a button in ppt and then bring it back into the iPad, but can't remeber how do do that -

is there a better way to insert some sort of play/pause control over the video during the running presentation mode?