Reported 2 weeks ago here on the forums and post ignored / copy paste canned responses. Videos don’t play on my iPhone either (not using the app, just visiting the site daily checking for updates. Checked with chrome and safari). iPhone 8+. Previews load, videos are just black boxes.
I already have a headset. I’d bet the majority of your costumers browse with a phone before putting it on, just like I do. I’d rather jump around and see if the videos are worth watching beforehand.