This PR adds a configuration option to control the preloading of video data on
page load with the HTML5 'preload'[1] attribute on the `<video>` element.
The option is enabled by default, meaning that the `preload` attribute's value
will be 'auto'. If users want to prevent preloading of video data, they
can disable the option, which will set the attribute value to 'none'.
[1](https://www.w3schools.com/tags/att_video_preload.asp)
Closes issue 4110
82ac9a8609
