If you are looking for a web based player for mid/midi files then you are wasting your time. Please keep in mind mid/midi is not a podcasting format.
You've more than likely been mislead. The site you linked to plays mp3 files when you click the play button. If you look closely, the player is literally an image that flips away when you click it.
http://www.8notes.com/scores/10128.asp?ftype=midisource: <audio id="demo0" src="/school/mp32/voice/schubert_ave_maria.mp3"></audio>
<audio id="demo1" src="/school/mp32/violin/schubert_ave_maria_kar1.mp3"></audio><audio id="demo2" src="/school/mp32/violin/schubert_ave_maria_kar2.mp3"></audio><audio id="demo3" src="/school/mp32/violin/schubert_ave_maria_kar3.mp3"></audio><audio id="demo4" src="/school/mp32/violin/schubert_ave_maria_kar4.mp3"></audio>
mid/midi files do not have a native player built into web browsers. This is why that site you link to uses mp3s in their custom built web pages to play the midi files in the browser.
PowerPress does detect mid and midi files as media files. We detect a lot of files that are not appropriate for podcasting. When possible we provide a player, when not we still detect the file size and display a player with a link to open with the media with the computer's default application.
If you go to (
https://wordpress.org/plugins/powerpress/) and browse further down to the "
Integrated Media Players" section, we clearly provide a list of the supported formats.
Player formats supported: mp3, m4v, mp4, m4a, webm, ogg, ogv, oga, wma, mov, pdf, swf, avi, mpeg, epub and more.
"and more" may have miss-lead you, sorry. We will take out "and more" and have our copywriter write something more appropriate such as "and compatible formats". The "and more" is for the many unique formats that blanket the formats listed, such as m4b and m4r (they refer to m4a files that are for ring tones and such).