confirmed the source of the top page after logging in via API Portal.
There is the following description there：
.....
if (typeof videojs !== 'undefined') {
 videojs.options.flash.swf = 'image/video-js.swf';
}
.........
It  seems API Poetal uses Flash.
However, Flash is not listed in the "Third-Party Software Acknowledgments" section of the document.
Does API Portal use Flash?

Release : 4.3.2

Component : API PORTAL

Normally Portal does not use Flash.  API Portal support videojs, but 
it looks like it might pull in a swf video player if html5 is not available.