If you check out this free lesson - http://guitartricks.com/freelesson.php?input=N21gNmM/N2w= - it says
... In this example I am playing at the 5th fret so I am in the key of A ...
But the video and the notation is in E. Just thought I'd mention it as it could be confusing, especially to new players.
Regards,
Buoy