It is working fine in Firefox and I have already searched for answers everywhere. I've reloaded Flashplayer and still video will not play. ESPN keeps telling me I need to install flashplayer and MLB.TV will not load. (As you can tell, I found these problems while trying to catch up on the baseball games) MLB.com just gives me a black screen where the video should be playing.
I installed Lion yesterday and everything else seems to be working fine.
Open a new user account on the computer and see if it will also not load in that user. If it does load just fine than its an issue with the one of the system files in your user related to safari or flash that is causing the problem. You can start by pulling the com.apple.safari.plist from MacintoshHD/Users/"your username"/Library/Preferences. In Lion you get to your user library by holding Option when clicking on the Go menu in the Menu Bar when Finder is the active application (next to the Apple). You can also look at the Internet Plug Ins folder in the User library, as well as clearing the cache files out of the Caches folder if the issue only happens in your user. If it also does not load in a new user than the issue is system wide with the application itself and might need a proper uninstall re-install. Also test sites where flash is used like CNN.com videos to verify its the plugin.