The article text provided consists almost entirely of PC Gamer's website boilerplate (membership sign-up prompts, cookie/tracking scripts and navigation elements) rather than the actual news content about the Call of Duty: Modern Warfare 4 beta. As a result, no substantive details about the beta dates, sign-up process or rewards mentioned in the headline are present in the text supplied.

I'm unable to produce an accurate summary of the actual article without fabricating details that weren't included in the extracted content. If you can provide the full article text or try fetching the URL again, I'd be happy to summarise it properly.