Multimedia has indeed taken the center stage when it comes to the content of any website. Simple test is not so simple, with CSS everything is more clean and beautiful. Compatibility with audio formats often creates trouble. The more the browsers, more will be the variation and differences between them. All the browsers aim at different ideal.
The biggest problem is that there is no standardization of formats or codecs of multimedia which must be used. But there are formats that are more cross browser compatible, the problem is when to use what formats. I can offer you an advice that you check this blog out.