So go to youtube and select any video because I think it is an issue
with flash objects.
Select the 'inspect element tool' in firebug and try to click on the
div that contains the flash player to select it and inspect it.
You should notice or at least I do that as soon as you move the cursor
off that div, the inspect tool will just go into 'hunt mode' again and
highlight all the elements it passes over. You will be unable to
select the div that contains the flash player.
Hope that explained it. I think I'm having the same issue with other
elements but right now, I can only see the issue with flash objects.
If I notice it happening with any other elements I'll post again.
Cheers!