Welcome to the community! Thanks for reaching out. Did you try using the other suggested browsers (Safari, Microsoft Edge, and Google Chrome) to see if it makes a difference? Did you try on incognito mode? Is it happening with these two videos or all the videos?
Try clearing the browser's cache and cookies, and after that restart the browser and see if that helps. For more information on how to clear cache and cookies check this article- https://adobe.ly/4eov6uw