Providing alternate media sources

The source tag enables us to provide alternate sources for the media. For example, alongside providing an MP4 version of the video, if we wanted to provide support for a new format, we could easily do so. Furthermore, if the user didn't have any suitable playback technology in the browser, we could provide download links to the files themselves. Here's an example:

<video
    width="640"
    height="480"
    controls
    preload="auto"
    loop
    poster="myVideoPoster.png"
>
    <source src="video/myVideo.sp8" type="video/super8" />
    <source src="video/myVideo.mp4" type="video/mp4" />
    <p><b>Download Video:</b> MP4 Format: <a href="myVideo.mp4">"MP4"</a></p>
</video>

In that case, we first specified a source of a made-up video format called super8. The browser goes top to bottom...