How to install video codecs on Windows 98
Windows 98 does not have many video and audio codecs (encoders and decoders) to play movies or music.
You cannot listen, natively, even an MP3!
For this reason, it is useful to add a package containing a series of tools and codecs like K-Lite Codec Pack. The last officially supported version on Windows 98 is K-Lite Codec Pack Full 3.4.5, downloadable here: www.3dfxzone.it/download/?object=file&objid=3575 or here http://www.eastbuttress.com/k4p/4
K-Lite Codec Pack Full contains also Media Player Classic a player that runs smoothly on Windows 98, probably better then VLC too.