"If genuine (I wouldn't know the difference, frankly) it brings so many questions to mind."
See current positions of Mercury, Jupiter, Earth, and Elenin on JPL:
There's no possible way you could see Mercury and Jupiter anywhere close to each other since they are more than 90 degrees apart from Earth's point of view. Elenin hasn't been anywhere near Jupiter during the entire time it's been in our solar system, since Jupiter has always been on the opposite side of the sun. Another problem with this video is that Elenin has never been between Mercury and Jupiter, from Earth's point of view, and certainly wouldn't move across the sky that quickly in one night.