Is there a way to disable participants' ability to change the playback speed on media files?

hey atorres1
maybe this thread also solves your problem :-)

https://community.qualtrics.com/XMcommunity/discussion/comment/44070
Best regards

Rudi

This JS will do that.

Qualtrics.SurveyEngine.addOnReady(function () {
	const quest = this;
	const qc = quest.questionContainer;
	qc.querySelectorAll("video").forEach((item) => {
		item.controlsList.add("noplaybackrate");
	});
});

Alternatively, you could just add 

controlslist="noplaybackrate"

to your video tag.