If you want to use 98, one soon discovers that the Internet Explorer 6 is good for nothing more. Microsoft updates there are none, because 98 is no longer supported for a long time.
Now you can try it with the last possible 98er version of Firefox, it is version 22.214.171.124 and it is on the offical server of Mozilla here:
The display of most Web pages is improved or possible. Well, YouTube can be as use, but there are minor graphical glitches.
Well maybe you want to watch Flash videos as well as on Youtube. The latest Flash version that runs under the Mozilla version is: 9.0.280
Here are the older versions available for download:
But it is certainly no fun, because the first is probably a weak computer (main reason for Win98) and the second has this outdated version of Flash poor acceleration. In short, it will be despite all bad.