The DVD format video, when it was recorded, the channel had a signal lost for an instant in two parts of the video. Just a few seconds are lost but the Avi format doesn't have any lost.
DVD image files are created with "Nero". To view the videos you have to download all parts to a special folder and join them with hj split. You can burn the DVD image with "Nero" (or a similar program) to reproduce in a DVD player, or you can open the DVD image file with Daemon Tools or Alcohol 120% (Both are programs that emulate CD/DVD Images). To reproduce the video in your PC I recommend Cyberlink PowerDVD player or Media Player Classic.