Spoiler alert: If you haven't finished Battlestar Galactica, I must warn you, you will find out who the last member of the final five is in this video*.
Humans don't stand a chance man.
*Probably not true. I haven't gotten through season 4 yet, but being clever I already know who it is going to be.
PS: I have now finished the series. And no Keyboard cat was not the final cylon to be revealed... which is frankly too bad...