I've been playing DVD movies that I borrowed from the local library and the problem I often encounter is the scene in the movie will freeze and then revert to a previously shown chapter on the disc. Sometimes 2 or 3 chapters. Sometimes back to the beginning of the movie. Before putting the disc in the player I'll check it to see if it has finger prints or scratches and use a very light spray of window cleaner with a tissue to polish them off. Being from the public library these discs get treated badly, and are also invariably scratched. I was under the impression that DVD discs are like CD discs in that it doesn't matter how scratched it is as long as it doesn't have any finger oil on it. My question is:Does it matter whether a DVD is scratched as opposed to a CD?

Scratches can and will cause CDs and DVDs to skip or be unplayable. There are disc resurfacing kits that you can purchase which can make an unplayable or skipping disc play again. If this is only happening with the movies from the library, and not with brand new discs, then I would not be concerned. However if this happens with all discs, even those in great condition, then there might be something wrong with your DVD player.

Do not... I repeat... DO NOT use those lens cleaning discs. They do more harm than good. The only good way to clean a DVD player is to take it apart and use a cotton swap on the lens. However, if you do this, please be aware that there are small moving parts in a DVD drive that can make it a real pain to put back together.