Watch free video HDRI Timelapse Sky As IBL And Backdrop

By using this HDRI sky time lapses, and using them as the IBL as well as the backdrop, you get intensely realistic lighting, and due to the real world changes in conditions due to ephemeral clouds passing, and the variation in shadow sharpness that this engenders, you end up with a much more emotive visual.
I threw this beta of one of their HDRI time-lapse into a test file I created some time back, and here's what the result looks like.