The finger thing is because your fingers are like .. joined in twos i think ( minus the thumb)... that's why if you bend one finger more go with it ^_^
Anyways. Try and do this FAST ->
if i were to number my fingers 1234 ( thumb is not included )
Put your hand on a table, and lift up 1 & 3, and then put them down and lift up 2 & 4
Good for co-ordination ^_^ I can do it uber fast :P