Do you have Norton Internet Security installed on your computer? If so, that's probably the culprit, and disabling it won't help. I had the same problem, I'll tell you how I fixed it and hopefully it will work for you too.
First, open Norton Internet Security. You should see four main tabs on the left, click the one which reads "Norton Protection Center" then click "Web Browsing".
In the "Web Browsing" window click "Ad Blocking" then choose "Turn Ad Blocking Off". Close all of the Norton windows then try your video player.
If this doesn't work or if you prefer not to do this, complete the above steps again but instead of clicking "Turn Ad Blocking Off" in the last step click "Configure Ad Blocking" then click the "Advanced" button. Here's where it may get confusing.
You will see that the "Advanced" window is divided into two sections, one on each side of the window. Click the "Add Site" button under the left section then enter "music.yahoo.com" (without the quotes) and click the "OK" button. You should now see "music.yahoo.com" in the left side list of sites. It may be under "yahoo.com" if you don't see it by itself. If you don't see it, and it's not under "yahoo.com" look for a plus sign next to "yahoo.com". If it's there, click it to open the list under "yahoo.com".
Once you find the "music.yahoo.com" which you just entered click it once to highlight it. Then click the "Add" button under the right side section of the window. Click the radio button next to "Permit" then enter "http://video.music.yahoo.com" (again without the quotes). Click "OK" then continue clicking "OK" or "Close" until all of the Norton windows are gone.
Your video player should now work. Good luck!
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