Question about Elecard codecs

I am a little bit confused about Elecard codecs.

In the download page of the ProgDVB site, for the MPEG2 codec there is a link to "Elecard MPEG-2 PlugIn for WMP".

For the H264 codec there is a link to "AVC PlugIn for ProgDVB" (40$).

But in the Elecard site there is also a "AVC PlugIn for WMP" (25$).

My question is: why do I need a special and more expensive AVC codec for ProgDVB, if there is also a generic codec for WMP?
And why there is not a dedicated MPEG2 codec also?

Thank you,