The light is coming from lights of course.. but the HDRI sphere is filtering everything to the right colors. This mkes it effectively coloring the lights from the right position. Specially at the lowest image you should be able to see that there's a lot of difference in colloring. ALL the lights are plain white though. And the ball is grey. So the colors on the ball are comming from the HDRI sphere. So yes... this is almost the same as true HDRI. Only thing you have to do is to make the white lights go through the sphere and let the sphere filter out the unwanted colors. It's basically the same principal. Only difference is that the image is set to color the lights here (whatever color the sphere is) instead of being a lightsource itself. The results can be exactly the same though.