I don't know about Ner0, but ImgBurn's verify does a byte level compare of the data read from the disc against the data from the source image/files. It's the most accurate type of comparison that can be done.
DVD players, on the other hand, simply skip sectors that can't be read, and usually the amount of lost data isn't enough to skip/freeze/drop-out the video stream. The thing is: you shouldn't be getting errors at all. If you do, it's most likely due to poor media quality and/or non-optimal burn speed/old firmware on the burner.