Microsoft has changed the interface on Stream slightly, so my code to export the transcript needed an update:

var objTranscriptLines = window.angular.element(window.document.querySelectorAll('.transcript-list')).scope().$ctrl.transcriptLines.map((t) => { return t.eventData.text; });
var strRunningText = "";
for(var i = 0; i < objTranscriptLines.length; i++){
    if( objTranscriptLines[i] ){
        var strLineText = objTranscriptLines[i];
        strRunningText = strRunningText + "\n" + strLineText;
    }
}
console.log(strRunningText);