Well, you're in the Dell Streak forums, a device which last saw an update 7 years ago. The 5" screen, introduced long before Samsung made them fashionable, only had a resolution of 800x480. The animation most likely matches, though the possibility exists that the actual images are smaller.  On your screen it will look tiny unless you modify the desc.txt file inside the zip to account for your screen. If you do that however the image will be fuzzy. On top of that, unless Samsung changed things, if you have a Samsung device you can't use boot animation zips at all. You'd have to use Samsung's tool and convert the boot animation to Samsung's proprietary format.
You probably will have better luck looking for a high res copy of the source and making your own boot animation.
My boot animation for this device used this trick to keep the size of the final zip manageable.