Uploaded my DreamSeeker.exe from that location to that site, says this.

It will be to do with the way certain games communicate with the user and what sort of traffic they're sending, I imagine. Just some suspicious behaviour on behalf of a BYOND game triggering AVG to throw up a false positive.

Lummox JR wrote:

This isn't a bug; it's not something we control, but a problem with AVG. It needs to be resolved at their end.

Although personally, I stopped using AVG some time ago. When they moved to version 8.0 the whole program became massively unstable, to the point where their updates started failing and their driver would block all Internet access after a reboot.

Is there any free anti-virus program you would recommend using?

I would try Panda Cloud it's free fast and great.

I've had the same thing happen to me recently as well

the reason for AVG blocking and removing Dreamseeker is cause this site and the games on here made that need Dreamseeker to run them are all 3rd party programs and aren't official at all and all have no security for them so every time you access Dreamseeker to play a game on here mainly if it needs online access to your internet signal its very easy to have a virus slip by during it, like I said this site has no security for any of this cause its all 3rd party unofficial etc

I've since taken Higoten's suggestion and switched to Microsoft Security Essentials. I find it a lot better and less resource intensive than AVG, and it hasn't given me any dumb false positives over things!

are all 3rd party programs and aren't official at all

All programs are third-party, in that neither you nor the antivirus software manufacturer made them. I'm not really sure what you mean by 'not official' - not made by Microsoft, or not personally endorsed by AVG? Sure. BYOND is a formal company though, I'm sure you can find them on whatever the American equivalent of Companys House is.

It's far more likely that AVG did what AVAST recently did for a while, and flagged BYOND as potentially suspicious because it's got a high volume of internet traffic and isn't a well-known program - the AVAST message actually explained something to this effect. ( Network traffic, low notoriety. )

Ahh, yes. The confusing and strange world of anti-virus scanning and Virus.Naming.Methods.
TL;DR: It's safe.

Now the explanation:

PUA.Win32.Packer.MasmTasm-2

PUA means 'Potentially Unwanted Application.' This means that whilst a file isn't a virus, or malicious, it may behave in a way the user does not expect.

Win32: it's a 32-bit Windows application.

Packer means that the installation executable uses a runtime packer. This basically reduces the size of the files you need to download, without needing another tool to unpack them. Think of it as an archive that can unzip itself.
The reason this is flagged is that viruses or malware often use this method to make themselves less noticable.

MASM and TASM are 32-bit assemblers, I believe. So this will, I assume, be the way the BYOND installer was assembled/compiled. All fits pretty neatly together;

The file isn't malicious, it's just bundled in a way that files which ARE malicious are often bundled; It's a 'Potentially unwanted application, on 32-bit Windows architecture. Considered suspicious because it used a runtime packer. Also, it was assembled using MASM/TASM.'

The other specific message I've seen is about non-proliferation of dreamseeker.exe or BYOND.exe. This seems to be because they're not widely recognised or profiled by antivirus engines, so it will err on the side of caution and flag the network traffic generated by games ( and constant communication with the pager/hubs ) as suspicious.

Well first off, which games and who are these 'known hackers?' That seems to be a title a great number of people on BYOND are willing to claim, and a great number of mislead or uninformed people are willing to attribute to someone. It's very rarely the case.

If you can answer those two questions I'll hazard a guess for you.