This video was pointed out to me the other day so I checked it out straight away on youtube and was blown away by how good it looks. The level of detail is seriously high, especially considering this is a fan-made production.
The guy (guys?) that made it can be found at www.thelordinquisitor.com or www.facebook.com/The.Lord.Inquisitor and they're eager to stress that it's not made to make money and is totally respectful of Games Workshop's IP. It's taken about 1.5 years of work and it's well worth it.
I hope that more is on the way, either an extended version or something different. I'd much rather watch this 3 minute trailer than the full Ultramarines movie any day.