Hi Paul.
I'm sure you came accross this few tomes but maybe just not familiar with the term.
VoiceTag is the voice stamp that plays & repeats on the background when the normal song/beat/music plays.
it doesn't fully protect against piracy but for the majority is small sites that want to monetize music/beat. But it is the traditional quick and dirty way to protect. Also it's usually a great and simple way to advertise while lisners are listening to the sample tracks in the player. Usually the voice tag is made so that the sound file can be loaded or replaced by the site admin when desired. So I would think it would be implemented as a LOOP that would sync with the main HTML5 player and starts/play/stop same time the normal player does.
Please listen to some tracks on the sites below & you will see the voice tags in action
http://www.beatstars.com/_mobile/#play:beat,DeepMentalz,beautiful-universe-16627,16627,25808
http://www.rocbattle.com/buy_beats.php
http://promotebeats.com/