html5 overflow ios,HTML5 video tag unreliable on iOS

I'm using PhoneGap to make an iPhone app that contains video. Usually, it works great: the video sits in an HTML5 video tag and it shows the iOS play button and then plays full screen.

But, sometimes the play button has a line through it and the user can't play the video.

I can't seen to figure out exactly what causes this, as it is sporadic and doesn't seem to be connected to any other issues.

Any help on making this more reliable would be appreciated. The code is a very simple video tag with src, poster, width and height attributes.

Thanks in advance.