I use DISCOGS_MEDIATYPE instead of MEDIATYPE because in many cases, the mediatype at discogs is not the same as my mp3s are from, e.g., discogs has often only the vinyl release listed when I have a web release mp3.
(See starting post for detailed listing of the tag fields the script is writing. Or open the exptended tag view in Mp3tag after you used my script: Alt+T 
)
Information like Vinyl, WEB, CD is more commonly stored in the SOURCE tag-field. But there is no clear difference to be between MEDIATYPE and SOURCE. Maybe MEDIATYPE should be used to store information like Album/Single/Best-of/Compilation/Live Recording.
Discogs's Mediatype combines both, so I left it as it is.
Open the script with a text editor and search the following part:
change it like the following:
The changes are marked in bold type. outputto "Mediatype" changes the tag-field to MEDIATYPE as you want it. The regexpreplace replace the mediatype form discogs with the word in the second quotationmarks with if one of the word in the first quotationmarks is found. You can expand that list and make alternatives as shown with Vinyl.
For a list of the used formats at discogs, look here http://www.discogs.com/explore > Formats > Show More
If you edit the script, you have to edit all versions of it. I recommend the freeware text editor notpad++ There you can edit one script and paste the changes into the others automatically. But it's tricky with multiline replacements.
See the discussion of FreaQ and stevehero above how to do this. Or look at dano's discogs scipt to see how he is doing it: /t/1992/1
I have not included this in the script, because
a) i don't know if how different mediaplayers display different formats at YEAR
b ) the information is not always there at discogs
c) release pages is about different releases of the same album (master release page). these different releases often do not have the same release date. this is also true for the year itself, but you see the different years in the discogs-search-page/mp3tag-websource-index-window. With the month it gets to complex and unclear. You would have to check every release page to see the different dates if you want to get sure you have the first release date.
d) as it is this complex, I think the release dates at discogs are not always correct, discogs users see the release date in their country and just asume it to be the global release date. And also the other way around.