base runner shading fielder's vision on a ground ball

8.4.2g is the rule in HS ball. The runner may not intentionally interfere with the initial play on a hit ball. The ball is dead, the runner is out, the batter/runner is awarded first unless the umpire feels the interference broke up a double play, all runners return.

Just to clarify, something I have seen many times. Man on 2nd, ball hit to SS, R2 times run to jump over ball right in front of SS - definately a deliberate action. SS distracted and misses ball. Does the above pertain to this?

The key word in the rule is "intentionally"...and the umpire rules on the intent of the runner.

I've seen many times that a runner has had to jump to avoid being hit by a batted ball. He is entitled to a straight run to the next bag and he risks being hit if he jumps over the ball. I can't say though, that I've ever called a runner out for "timing" his run so he would have to jump over the ball. I have called runners out however, for stopping or dancing in front of a fielder in an obvious attempt to distract him.

pilsner is right about just running not being a problem. I have seen some stop or greatly slow down to make the jump over the ball be right in front of the fielder. If the umpire thinks he does this to time it to interfere then get the out. Obviously the stop or dance in front of the fielder is going to be automatic.

the runner can "time" his run so the batted ball goes right under him (in front of the fielder) legally...this is done all the time. The KEY is, once the runner starts to move, he does not stop, hesitate, delay, etc at the intersection of ball and runner - once under way, he continues more of less continuously.