Which is why film work is so critical. Even then, you have to know what you are looking for. Example, camera angle needs to be changed during BP so that you can see several angles on a swing. You might not notice from a side view that a player is seperating their hands away from the body on one camera angle and yet, from another, you'll see it right away. Another example - "being on time" during breaking pitches and fastballs requires a series of movements (timing even though swing is the same - your batter might straighten up with a breaking pitch) in conjunction with ball flight. If you don't have a couple of angles that demonstrate ball flight, you might misinterpret some swing mechanic. Just a few thoughts!