simulating fluids in real time is difficult - and very demanding on hardware (which means it doesn't work too well on mobile devices).
the lava in the video looks like it was pre-animated, because the ripples are always exactly the same. Doing "fake" ripples with an animation like that greatly reduces the work load for the cpu and will then run fine on weak hardware.
the last time I played around with water was a few years ago - see this forum thread:
I don't know if any of the other samples are still available, but the demo and download in my first post there still work... (click on the screen to make a splash, or press space bar to make waves. I think it requires the Paster plugin)