Home Sharing works on everything but iPhone 4 video

I have Home Sharing enabled on my iMac. My iPad, 2 iPod Touch and Apple TV all see it ok.

The iPhone 4 has home sharing enabled in both the Music and Video settings. It sees the shared Music in the Music app but there is no Shared option in the Video app on the iPhone.

I have rebooted the iMac, switched on and off home sharing in iTunes, rebooted the iPhone.

Can anyone shed any light on what is going on here?? Everything is running the latest iOS5 versions.