I cannot use my microphone! HELP!

I would try clicking all around in the area inside and near the Permitir button.  Sometimes the "hit area" for the click is offset a little from where the actual button is drawn.  In other instances, particularly if there are moving things near the border of the dialog, our security controls think that the dialog is obscured and won't register the clicks as valid.

If you can't dismiss that dialog, instead, go to Control Panel/Settings > Flash Player.  Choose the Camera and Mic tab.

Click the Camera and Microphone Settings by Site button

Click the + button, and add www.japanesepod101.com to the list.  Choose Allow on HTTPS and Other.

This should allow the page to access the microphone by default.  At that point, you should be able to refresh the page and the dialog should be suppressed, since you've explicitly granted it access.