The swap meets sell lots of pirate CDs and DVDs; most are in English with Spanish sub-titles. However, pornography is illegal in Mexico so you won't easily find xxx DVDs.
The last time I was in Todos Mercado there were several places selling 5 DVDs for $10.00. (Be sure they are compatible with region one unless you have a multi-region DVD player, which isn't expensive and can be purchased in San Ysidro.)
If I remember correctly there are places on Constitution and Ninos Hereos (around 3rd) that sell CDs and DVDs. I believe they can also be found in the swap meet on Revolucion between 9th and 10th. But you'll find a larger selection in the large swap meets, like Todos and Siglo XXI.
The last time I was in Todos Mercado there were several places selling 5 DVDs for $10.00. (Be sure they are compatible with region one unless you have a multi-region DVD player, which isn't expensive and can be purchased in San Ysidro.)
If I remember correctly there are places on Constitution and Ninos Hereos (around 3rd) that sell CDs and DVDs. I believe they can also be found in the swap meet on Revolucion between 9th and 10th. But you'll find a larger selection in the large swap meets, like Todos and Siglo XXI.