Yes i did use the 'WD Photos' app which can be used to transfer video and photos from your iPhone via WIFI to your WDTV Live Hub. It works pretty nice. And all video and photos work nicely.
I also use the Zappo.tv app (free) which has the option to search e.g. YouTube videos on your iPhone and play them on the WDTV Live Hub this is a lot quicker then using the remote control (if you don't have a keyboard connected to your WDTV.