Unlike its laser-based counterparts, the chapters in a CED are based on minutes of the film, not scenes. Novelty discs and CED-based games were produced whereby accessing the chapters in a specified order would string together a different story each time. However, only a few were produced before the halt of CED player manufacturing. Disadvantages In comparison with LaserDisc technology, CEDs suffered from the fact that they were a phonograph-style contact medium: RCA estimated that the number of times a CED could be played back, under ideal conditions, was 500. By comparison, a clean, laser rot-free LaserDisc could, in theory, be played an unlimited number of times (although repeated or careless handling could still result in damage). Since the CED system used a stylus to read the discs, it was necessary to regularly change the stylus in the player to avoid damage to the videodiscs, while worn and damaged discs also caused problems for consumers. When a disc began to wear, video and audio quality would severely decline, and the disc would begin to skip. Several discs suffered from a condition called "video virus", where a CED would skip a great deal due to dust particles stuck in the grooves of the disc. However, playing the disc several times would generally solve this problem. Unlike VHS tapes, CEDs (along with LaserDisc) required a disc flip (however, some LaserDisc players were able to read both sides of the disc without physically flipping the disc, achieved by moving the laser from one side of the disc to the other, but this still resulted in a pause of playback during the change) at some point during the course of almost all films as only sixty minutes of video could be stored per side (75 mins on UK PAL discs due to the slower rotation speed); if a feature ran over two hours, it would be necessary to spread the feature over two discs. In some cases, if a movie's theatrical running time was only slightly longer than two hours, studios would often trim short scenes throughout the movie and/or employ time compression (speeding the extra run time out of the film) in order to avoid the expense of issuing two discs. This problem was not unique to CEDs: LaserDiscs presented the same difficulty, and some longer features, such as The Ten Commandments (1956), still required more than one tape or disc in the