[nabs-l] pop-ups when clicking on a video

[vejas]

Hi,
Today I was trying to play some videos on Kahn Academy (which 
many of you probably have heard of, it helps people with 
schoolwork and also has informative videos.) Anyway, when I 
clicked on the video, a pop-up thing opened, and wouldn't allow 
the video to play.  I had to have my dad help me play it by 
closing the pop-up with his mouse.  How do you get around these?
Vejas