To promote a monster movie, Sony Pictures installed a holographic rig in Tokyo Bay that projects the monster onto a haze of water.
The feat uses a water screen (carefully sprayed water jet) and exact light projections to create a giant pseudo-3-D Loch Ness "Water Horse" monster in the bay.
What you're seeing in the video wasn't added after the fact—that's actually what it looks like in real life.
http://www.liveleak.com/view?i=355_1220225911
Wow, Thats pretty impressive. To have been able to see it with your own eyes I bet would have been just awesome!
Thanks for the video Mayhem :/\