gistfile1.html

<div class="btn-group" id="yui_2_5_0_1_1401293648379_841">
    <button type="button" class="btn btn-default btn-default-content yui3-widget yui3-btn yui3-btn-content yui3-btn-focused" id="yui_2_5_0_1_1401293648379_876"><span class="glyphicon glyphicon-ok-sign"></span> Save</button>
    <button type="button" class="btn btn-default btn-default-content yui3-widget yui3-btn yui3-btn-content" id="yui_2_5_0_1_1401293648379_840">Cancel</button>
</div>

YUI().use('aui-base', function(Y) {
    var buttonList = Y.all('btn-group button'),
        buttonSave = buttonList.item(0), // "Save" is the first button
        buttonCancel = buttonList.item(1); // "Cancel" is the second button

    console.log(buttonSave, buttonCancel);
});