I registered cod4.org a few hours ago and immediately changed the name servers to the correct ones for my server.

4 hours later, the domain still redirects to Namecheap's parking page, even after I did a DNS flush on my computer

What I don't get is if I try to visit the domain with a proxy, it goes straight to my server, like it should.

Why is it that the name redirects properly to its correct server on a proxy, but still goes to Namecheap's parking page on a normal Internet connection?

Based on what you described, and if both WHOIS and your account confirm the domain name is using the correct set of nameservers, then I'd say it's your ISP. ISPs refresh their DNS cache at their own pace.

The site's pulling up fine on my end. (Manila)

Well same thing happened to me but it worked after 3 days, i don't know how.

What I don't get is if I try to visit the domain with a proxy, it goes straight to my server, like it should.

Why is it that the name redirects properly to its correct server on a proxy, but still goes to Namecheap's parking page on a normal Internet connection?

It's like Dave Z. says - your ISP has a set of recursive nameservers which look up host records for your browser, etc.

These ISP nameservers are set to cache all results for a length of time your ISP determines. Sometimes it's 4 hours, 12 hours - I've even seen 3 days!

When you go through a proxy, you use a different set of recursive dns which doesn't have a cached value, so they go out and retrieve the fresh result.