This is an unfinished short from animator Paul Michael Johnson, and it briefly made the rounds back in 2012 before we had the hope of an actual good Star Wars film. Fans went pretty crazy for the short back then, and it's not hard to see why.
I stumbled upon it again when I was searching YouTube for cut Star Wars footage, and I've watched it multiple times across the last week, trying to figure out why I found it so striking. It does a great job of showing off the strong design of the ships from the original trilogy, and it also goes out of its way to point out that these are people piloting each and every one.
It also shows us something we have yet to see from any of the pre-release teasers and trailers from the upcoming film: battles in space. Star Wars director and writer George Lucas famously emulated scenes from World War 2 films when directing the original space battles, but this short shows just how dynamic those fights can seem when someone isn't afraid to move the camera a bit more.
If nothing else, give it a watch if you've never seen it. It's great stuff.