gecko/toolkit/themes/pinstripe/global/media/videocontrols.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

.controlBar {
    height: 24px;
    background-color: #656363;
}

.playButton {
    list-style-image: url(chrome://global/skin/media/videocontrols.png);
    -moz-image-region: rect(0px, 48px, 24px, 24px);
}
.playButton[paused="true"] {
    -moz-image-region: rect(0px, 24px, 24px, 0px);
}

.muteButton {
    list-style-image: url(chrome://global/skin/media/videocontrols.png);
    -moz-image-region: rect(24px, 24px, 48px, 0px);
}
.muteButton[muted="true"] {
    -moz-image-region: rect(24px, 48px, 48px, 24px);
}