The player above is our S3 Streaming Audio Player, Demo #1. It is a AES 128-Bit Encrypted HLS Audio Stream, which makes it practically impossible to download.
There is no mp3 file – it's streaming audio. So there is no single file to download. It's a running stream of files, which are all individually encrypted. So even if someone found a way to download the various "pieces" of the audio, it won't work with any audio player, because the parts are encrypted.
S3MediaVault is the World's first WordPress Plugin to offer Encrypted Audio Streaming as well as Encrypted Video Streaming.
And if you want a regular, standard audio player (progressive download), then S3MediaVault has one of the prettiest audio players available.