How to cover a water stain on drywall

http://www.VideoJoeKnows.com How to cover a water stain on drywall is discussed on this short howto video. So
you have a water stain on your drywall & not sure how to tackle it. Can you cover the water stain with drywall
joint compound? Will that cover the water stain? What if I just use regular primer but apply 2 coats of primer
rather than one, over the water stain. Won't that work? Oh......I have to use 2 coats of a finish paint then the
water stain will be covered....right? I hate seeing old water stains on my drywall & it seems like whatever I do
they reappear. What am I doing wrong?
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