Hello,
If what you are saying is true, then it is indeed not illegal. For something to be illegal (infringing on copyright laws) it would have to be a copy or a non-original backup of the DVD. Someone selling a DVD that they legally purchased infringes on no laws anywhere that I know of.
Does this take profit from the producers? Sure it does, but again one person is not going to make a significant difference to the industry. Businesses like Theory11, LLC., Ellusionist.com, LLC., and L & L Publishing, LLC. purposely market their products to adjust to losses. This is all reflected in prices, hypes, and other products that they are able to pull a revenue off of.
Take a look at the Wynn playing cards or Theory11 exclusive decks. They are all sold roughly for five-seven USD. The cost of each deck ranges from $1.50 to $2.00. Thats over a 300% markup. These publishers are getting a piece of their pie, so don't put too much worries that they are not making enough money, I am sure they will be fine.
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