Ben Crane has an excellent golf swing, but he makes these swing errors:
1.     At address, Ben stands a bit too stiff-legged.  It is better to put a little more flex in your knees, so the leg muscles are less tense and better able to deliver maximum power at impact. He could be sacrificing some distance on his shots because of this flaw in his stance.
2.     During the backswing, Ben’s left knee pops out, away from his body, instead of working toward his right knee.  This affects perfect balance at the top of the backswing, as your weight is likely transferred to the right heel and outside of the right foot instead of where it should be—the inside of the right foot.  Perfect balance is a key factor in the player’s ability to smoothly and quickly start the downswing back to the left side with a hard leg drive, thereby delivering maximum power at impact.  Ben may be sacrificing some distance on his shots because of his left knee movement on the backswing.
3.     As his backswing reaches the top, Ben does not quite make a big enough shoulder turn.  To deliver your most powerful strike at impact, it is critical to combine a restricted hip turn with big shoulder turn, creating the strongest possible coil in your upper body, which your legs lead through impact.  Although Ben restricts his hip turn, he is sacrificing distance on his shots because his shoulder turn is not quite big enough to create a very strong coil in his upper body.
Please see Golf Swing Fundamentals Checklist blog entry for a complete and detailed explanation of the key fundamentals that produce the perfect golf swing.