For under $500 you're not going to get much. If you could extend your budget to like 8-900 you'd get much more. Look for a dedicated graphics card like the Nvidia Geforce GT630m. Acer V3 has one for $520 with a i3 and that. HP DV6 can be customized with the i3 and 630m or the amd A10/A8 with a dedicated amd graphics card. Check those out.
Do you want 15 or 13 or 17 inch? You'll probably want a quad core processor, but it might not help if your editing program doesnt support rendering with all 4 cores. A dedicated graphics card is more for gaming, but can usually speed up rendering (its called gpu acceleration)
I just bought my self a new editing/gaming laptop so I've reasearched a fair amount. Mine was $550 with a AMD A10 APU with dedicated graphics, which works pretty well for gaming and editing.
HP Computers aren't known to be the best quality so you might want to get another brand but for $5-600 they have some pretty good deals. Just remember, the processor and graphics card matter the most. Get quad core and dedicated graphics if you can.
"take deoxyribonucleic acid for example. Sound's impressive right? Ever see what happens when you put something in acid? It dissolves. If our bodies were all full of that acid, we'd all dissolve. So much for the theory of evolution."