I found the fix in
another thread. I've copied it below. Works perfectly.
Thanks to
unicolondon, the unsung hero of the Safari-Youtube debacle of 2011.
System configuration:
Safari Version 5.0.3 (6533.19.4), Mac OSX 10.6.6
My wife's computer suffered the same problem and I managed to compare her settings with my MacBook and I noticed that safari had an unwanted plugin with .exe format that was preventing youtube to automatically load its videos.
the plugin was: NP-PPC-Dir-Shockwave
After removing it safari it all went back to normal again.
to check your plugins:
goto safari/help/installed plugins
Understanding the Safari Plug-ins List
Plug-ins are actually files within files. Safari groups plug-ins by the file that contains the small programs. An example that just about every Mac Safari user will see on the Installed Plug-ins page is the QuickTime plug-in. A single file called QuickTime Plugin.plugin provides the code that runs QuickTime, but it’s actually made up of dozens of individual codecs for playing back various types of content. (Short for coder/decoder, a codec compresses or decompresses voice or audio signals.)
Other types of plug-ins you’ll probably see include Java Plug-in for Cocoa, Shockwave Flash, and Quartz Composer. If you want to remove a plug-in, you need to know its file name. To find this information, look through the plug-in descriptions on the Installed Plug-ins list. For example, to remove the Shockwave or Flash plug-in, look for a Shockwave Flash entry in the Description column for the Flash Player.plugin. Once you know the file name, you can remove the plug-in file; this will uninstall the plug-in from Safari.
How to remove unwanted plugins
Safari stores its plug-in files in one of two locations. The first location is /Library/Internet Plug-Ins/. This location contains plug-ins that are available to all users of your Mac, and is where you will find most plug-ins. The second location is your home directory’s Library folder at ~/Library/Internet Plug-ins/. The tilde (~) in the pathname is a shortcut for your user account name. For example, if your user account name is Tom, the full pathname would be /Tom/Library/Internet Plug-ins. This location holds plug-ins that Safari only loads when you log in to your Mac.
To remove a plug-in, use the Finder to go to the appropriate location and drag the file whose name matches the description entry in the Installed Plug-ins page to the Trash. If you want to save the plug-in for possible later use, you can drag the file to another location on your Mac, perhaps a folder called Disabled Plug-ins that you create in your home directory. If you change your mind later and want to reinstall the plug-in, just drag the file back to its original location.
After you remove a plug-in by moving it to the Trash or another folder, you’ll need to restart Safari for the change to take effect.
I hope it helps for you as well.
