If an article has supplemental files available, there will be a Supplements button in the bottom toolbar. Click this button to pull up a menu of the available files. You can open some file types directly within the Web Reader, including PDFs, images and videos.

Once open, you will notice several available features along the top of the screen.  From left to right, these allow you to zoom in, zoom out, fit to screen, and download the supplementary file.

If you open a video supplementary file, an embedded media player will open in the center of your screen.  Click the central play button to begin viewing the video.  To pause, press the pause button in the lower left.  There is a full screen option available in the bottom right of the video player.  To close out, click outside of the embedded media player.