Thank you both for your input. I'm hoping that they will start playing nicely together.
Here is the video of them running and playing:
http://i1137.photobucket.com/albums/...a/f154f7a9.mp4
Kizzie - great suggestion about throwing toys!
Susan - you have 4 yorkies! How fun! Thanks for sharing. Sassy sounds like she can sure take care of herself!