I reckon, with camera evidence, several unsuccessful recent penalty kicks should have been retaken as the keepers had infringed the law .. moving out of a vertical plane passing through the goal line .. a penalty kick is really meant to favour the kicker.
------Law 14 states that the goalkeeper 'must remain on his goal line, facing the kicker, between the goal posts until the ball has been kicked'.
The goalkeeper may move anywhere along the goal line from side to side, before the penalty kick has commenced, this includes jumping up above the goal line which extends in a vertical plane upwards. The penalty kick is legal, so long as the goalkeeper does not leave the plane of his goal line, or does not move into the field of play before the ball has been touched.
If the ball entered the goal and the penalty taker had infringed the Laws before the ball was in play, the penalty kick must be retaken. Any hesitation during the run up, clearly attempting to put the keeper off-balance before taking the kick could be construed as unsporting behaviour - in which case the player concerned could also be Cautioned, and the kick retaken if a goal was scored.
The kicker is allowed to feint and conceal his intention from the goalkeeper but he must approach the ball in a single fluid movement. It is not allowed, for example, to fake a kick and then shoot in one direction after the keeper has jumped in another.