Sony MD, 999 month warranty. Tested, results inside.
Well, I was bored and noticed that Sony has a 999 month warranty on their MiniDisc's. So I threw the disc into a wall, jumped on it, threw it across the yard into the fence (which caused the metal slide to come off, but it places back on very easily). Then the final test: Running it over with a car. So I put it undernear the back tire of the van and ran it over 3 times (backed over it with rear and front tires, then drove over it again with the front tire). To my suprise, it was still fine. I took before and after pictures, but if you don't believe me I'll take a video of it getting run over. Anyways, the Sony medium certainly meets my approval. :)
Also, I'm not sure how much pressure was on the MD when I ran over it. The mechanic said that the engine puts over 600 pounds of pressure on each tire at the front (I asked when the tire seemed to be going flat, but he said that it only looked like that because of the engine, and gave me an estimate of how much pressure it put on each tire).