This takes the "I'm not a robot" checkbox to its logical step. By checking speeds and tracking mouse pointers you can easily determine if a user is a human or automated bot. 

Test automation or spider bots for example run at high speeds to test the page and retrieve information whereas humans generally have to contend with a reaction time of finding and clicking on an element.

So how can I get around this with my selenium testing?

The answer? Probably with great difficulty as Google will have put a lot of effort into getting their algorithm right and it will be constantly learning.

What you can do though is try and slow your tests down. For example by using Selenium's explicit wait methods or Thread.Sleep(5000). Be sure to override the SendKeys method especially so that it waits between key presses.

Until Google & Mozilla release a new Selenium version with added functionality we will have to hack behavioural tests in order to make them work with the new system.