Such a misleading statement.
If your discs work in the way you wish them to perform and still work that way in the coming years then the combination of media, drive, firmware, player etc are said to be 'good'.
Just because a 'movie' plays back fine on your given player does not mean the media is going to be par for the course. Also if the movie is not using the 'maximum' byte value of the media AND tested at that capacity at it's rated speed and scanned, there is no telling how good this media is going to be for data storage (Video on DVD's inherently allows the skipping of bad portions of a disc - sometimes imperceptibly whilst viewing the video - during playback.). Also some dyes have been known to go bad faster than others (Some say Princo media has gone bad after only a short period and made the media difficult if not impossible to read).
Just to clear that misconception up (and piss off those who presume too much from a wizz of their 'oh so perfect' burns in their $30 PioSonyBishi DVD player)