I hope to keep up with posting some baseball videos moreso than I did with basketball, and hopefully this will give you something to think about as you head to the ball field this spring/summer.
One key thing to remember is that you need to shoot wide open or close to it. If you've got a 300/f2.8 or 400/f2.8 you might be able to get by with f4 as I did in these examples. If you're shooting with a shorter lens (like a 70-200/f2.8) you'll probably want to be wide open.
Good luck and happy shooting!