Lab… that could depend on many factors. It is true people stay away from Memorex generally because you never know who the manufacturer will be. The program I will mention below can identify who made the Memorex, which could possibly be CMC or Ritek with Memorex, although another DL maker is MKM. If it’s identified as Ritek as the maker, most things Ritek in the DVD media variety is mostly trouble.
That said, I would encourage you to go to this site, with the link in this article(http://www.cdfreaks.com/news/13931), and download Nero CD-DVD Speed 4.60. This of course assumes you have a DVD burner in your computer (like a BenQ or LiteOn) that is capable of quality scanning. For example, I have a BenQ 1640 and a LiteOn 165p6s in my machine, and both can do this using CD-DVD Speed. If you have one of these brands of burners, put your DL disk in, run CD-DVD Speed and do the “Disc Quality” test and the “Benchmark” or “Transfer Rate” test. These tests can help you see how well or how poorly your disk burned, and can possibly identify quality issues, based on PIE, PIF or even POF readings generated under the Disc Quality test, and if you get major dips downward on the “Transfer Rate” test, you could be dealing with major reading slowdowns of the data on the disk, which could affect playback. Generally, if the Transfer Rate graph has dips, you could have read trouble where the dips occur; if it is a smooth upward curve, your data is read without problems.
A bad disk could do several things: you could see pixelation (blocks of color) during playback; some transitions between scenes could freeze, then restart, or you could even put a disk in a player (it worked before), but now it will not even read it (and therefore not play it).