Good job with the deeplinking and resizing! You could have them up to 800 x 600, but this size is fine as well.
Your entry looks pretty nice!
There are some nice details like the crossed swords over the map and the sinister-looking skull and crossbones on the wall( good idea there). Good job tiling the floor, it makes your entry a lot smoother. The plume acting as liquid spilling out looks excellent as well.
Non-MOC related improvement suggestions:
1) Firstly, I would recommend writing a little backstory, so that viewers know what's going on in your entry. Just something short would be fine, as long as it explains the basic concept.
2) For your pictures, taking them against a white background (some large pieces of white paper or posterboard work great) and using the macro feature on your camera if you have it should make your pictures much sharper and brighter.
MOC-related improvement suggestions:
1) The pirates don't really look like they care too much that the soldiers are stealing their loot. Perhaps using some angry, concerned faces would work better. The Power Miners sets have some good ones.
2) You could possibly make your entry a bit larger, so there's more room for design elements and details, but that's up to you.
3) A torch or lantern might look nice on one of the walls. You could use a design like in the pirate sets, a trans-yellow round 1 x 1 brick inside a black palm tree holder, with a dish on top.
That's about it for now. You have a nice start on this, and with some better pictures and perhaps a little change here and there, it'll turn out great!
Good luck for the contest!
EDIT: It looks like you've added a story now, so don't pay attention to suggestion number 1.