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Check your DVDs for disc rot — Warner Bros. says it’s replacing them
(www.theverge.com)
This is a most excellent place for technology news and articles.
Huh, if that doesn't work there are a few websites that will show you info about when the dvd was released
Unfortunately, that doesn't help, since most DVDs in the world were not manufactured in the first production run.
Sorry that wasn't clear, there are websites that let you look up info from the barcode