Well...I have just seen the video.
to me it seems to be a more fancy way of entering a simple Virtual OS.
We will have to wait and see how it's resource usage would be.
I personally do not like the idea of a new UI, If it were me I would prefer to mimic the existing desktop (keeps the user working) than to bring the user to a new UI (User starts to get confusion, often tries to play with things unnecessarily).
Standalone or integrated, this is a good idea, but I would like to see this to be more productive and as Melih said, a better Comodo's Sandboxie.