Ensure browser is updated. and may fix HTML5 video error. It is a good idea to always include width and height attributes. HTML5 video should work in Firefox web browser. Step 1: Change the video quality by going to Settings in the corner of the … New Jersey 08840, United States. Are you unable to watch videos on Vimeo, YouTube, or other websites due to the ‘HTML5 Video File Not Found‘ error? Most sites are using it. Please reload CAPTCHA. 350 million people use Opera daily, a fully-fledged navigation experience that comes with various built-in packages, enhanced resource consumption and great design. click on the three vertical dots on the top right, Choose and tick the checkboxes: Browsing history, Download history, Cookies and other site data, and Cached image and files, Click on This site contains user submitted content, comments and opinions and is for informational purposes only. You deserve a better browser ! Turn off any adblockers or extensions in browser. We’ve covered the basics of adding a video to your web page using the