How to determine if False Positive or a Virus?

I read many threads and see it again and again - someone posts Virus Total scan with a warning, and then OP will respond "false positive".

I got Scrapebox, licensed form the developer, with VirusTotal warning, support says "false positive".

How does one actually determine if it is a virus or not? You can't just believe when someone through the "false positive statement" at you, but how do you verify it?

you can submit the files to AV site for further testing and they will email you the result. i'm a scrapebox user and usually the addon like chess game trigger my AV (Avira), so what I did is submit the addon to their site and the result was false positive.

wicked thank to you
where exactly on the site do you submit it to? do they have some submit suspicious file section?
how fast they Analise it? or it's automatic instant report?

I think almost AV software has a section where you can submit suspicious file. Since I'm using Avira antivir and it detect one of the addon as a trojan I submit the sample file to them to test and the result was false positive, not a real virus. They have a page that accept submission for suspicious file.

You may want to run an outbound firewall like Comodo or ZoneAlarm. This will tell you whenever a program you are running is trying to contact a server somewhere.