The "chroma bug" is an MPEG decoder error. Once you know what to look for, it is very easy to spot.
If you don't know exactly what it is, my advice is: DO NOT GO LOOKING FOR IT! If you learn to spot it you will become sensitized to it and you will see it all the time. There are very, very few DVD players on the market that don't exhibit the chroma bug to some degree, so if you go looking for it you will do nothing but create problems for yourself. Don't ask how I know :-(
YOU HAVE BEEN WARNED.
