How to enable H.264 in Windows XP?

[TryKindness]

I noticed that a system was provided for Linux and OS X to enable H.264 playback using external files.
See here: https://www.slimjet.com/en/libffmpeg.php

Isn't there a way this can be done for Windows XP users as well?
Perhaps using ffmpeg.dll or avcodec-lav-57.dll & avutil-lav-55.dll?
Also, I have been able to get Widevine to install in Slimjet and it appears to be functioning properly (DRM websites such as Spotify recognize it as functioning properly). It seems the only thing standing in its way is the lack of H.264 playback ability.
So if we could get H.264 working it appears Slimjet could be a very useful, fully functional browser for XP users.

[XPloRR64]

Looking for the same.
Any news?

[oftentired]

One solution that I suggest is to install Vista and use the update suggested in this Blog