Gareth Edwards did produce the 250 HD effects shots all by himself. Gareth was using Premier Pro, After Effects, mocha-AE, PhotoShop, 3D MAX and some more tools. Gareth spend almost 5 month on the post production.
fxguide did publish a great background story on the making of “One Man Against Attila the Hun”
“Every once in a while we get a story at fxguide that indicates just how far and how fast the industry is moving. The post on Attila the Hun, directed by Gareth Edwards, is one of those stories. Edwards produced the 250 HD effects shots by himself in five months using After Effects and Photoshop. Averaging 2 shots a day, it was one man against the armies of Attila the Hun…. Read the rest of the story on fxguide”
Make sure you watch the Quicktime movie that is on the page click on “Edwards prepared a shot breakdown QuickTime movie which you can download from fxguide.”