FIX YOUR SITE
This happens all the time.. Yahoo has an awesome story with vids or pics I want to see... So I click on it and BAM!! video never loads and pics never show up. I'm officially removing Yahoo.com as my homepage.

Hi,
There are some additional steps to improve the Yahoo Tech video quality on Safari.
Check your browser version, and make sure you have the latest version installed.
http://whatversion.net/safari/
If you’re still experiencing issues and are using Safari 5.0, please update.
http://support.apple.com/downloads/#safari
Please let us know if this helps!
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Dashiell Oatman-Stanford commented
Try disabling AdBlock. You don't have to turn it off completely if you don't want to -- just add Yahoo! to the list of pages that AdBlock does not affect. Worked for me.