When buying DVDs from someone, be sure that they are genuine and are not copied or pirated. I bought some DVD's off tequiero2020 for £20, but they were copied and in bad condition! I had to track him down about it because it was pirated (selling copied material illegally). He may act very friendly and helpful when trying to sell you his wares, but please be careful.
Another cheat pirater I have encountered is ruggerbuggerclub who also copies and sells pirated DVDs. He will not accept refunds.
Both the above have been reported to FACT who concentrate alot on Ebay piraters. One such dealer on Ebay was jailed for 6 mths recently.