Custom buttons can be added directly via the dashboard under your video configuration, see the buttons menu in the left-hand menu.
You can select any icons from font awesome here we have selected vimeo and youtube for this example.
Live Example Below
AWS media audio.mp3 will be displayed here...
HTML Direct insert. You can use this codepen to create your data setup. https://codepen.io/s3bubble/pen/RLGKee
<div class="s3bubble" data-setup='{"codes":["gNZZ74083"]}'></div>