Few days back I found wasp dragging a spider and didn't know what was going on, this clip on YT is very similiar.
http://www.youtube.com/watch?v=hEEUGJG53r8
Not video but I have several stills of this scenario. I took them in May at our home in Spain. The wasp actively hunts the spiders amongst ground cover plants, chases it into the open and then a battle commences, in our case the wasp won and almost got away with its prey. This wasp in particular was really aggressive, it let me get to within 3 feet with the camera and then went on the offensive, rearing up on its legs and advancing towards me. Three times I tried to get close and three times it did the same thing.
I did the only thing I could, I emptied half a can of wasp spray on it to get it out of the garden
The spider was well dead. Finger shows just how big these two brutes were.