Need help on Beta Testing and Security argument

Hello,

My partner and I have been developing a flash game for quite a while and are only a few months away from releasing it. My partner would like to beta test this with strangers from the internet, while I prefer to just beta test it with people we personally know and trust. My worry is that the beta will be stolen and distributed on the internet before it gets sponsored, destroying any potential reward for all the work I put into it. His concern is that the game needs many testers in order for it to reach it's optimum quality.

Am I just being too paranoid about having it stolen during beta testing or are my concerns justified? For any professional developers, what do you do in regards with beta testing? Does anyone have any tips for security? Any other suggestions?

Thanks!