Hi Jacky,Unfortunately codec issues are common because there just so many types of compression (codecs) used for videos and every computer will have different codecs installed.
Personally I try to stick to just a couple of video formats that I know give good results. Trying to support every type of video on your system is likely to cause more hard than good.
If you want to use AVI video, try installing DivX or Xvid codecs. For .MOV format install the latest Quicktime. On top of those, you can use WMV as most Windows systems will support this without requiring additional codecs.
Then if you run into problems with a video, use a Video Converter to convert to the format of your choice. A great video converter is Format Factory and it is free. :)
http://www.formatoz.com/index.html