Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
It works fine on all of my Leopard boxes, so a little more information would be helpful:

Do you have the latest version of Flash installed (115, I believe)?
What browser are you using (or is the problem the same in all browsers)?
What Mac and how much RAM?

Also, slow I get, but what in particular is "strange" about it--page looking funny when it loads, weird behavior with the video controls, etc...
 
The latest version of flash (9.0.115) has a documented video performance issue, especially when multiple flash objects are embedded on a page. All you can do is wait for Adobe to fix their junk.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.