Play Button To play the videos, click the play button or click anywhere in the video window or select a chapter from the list.

Pause Button To pause the video without losing your place, click the pause button or click anywhere in the video window.

Captions Button Clicking the CC button (off by default) will toggle closed captions on and off. If the CC button is not present, closed captions are not available for that video.

Quality Button Clicking the Quality button will toggle between a high definition 720p; 2144kbps video stream (when available) and a lower resolution 360p; 1144kbps video stream. The player defaults to 720p. If the video takes a long time to load or doesn't play smoothly, select 360p to watch the low resolution stream.

Fullscreen Button Click this button to watch the lectures in full-screen mode. This is recommended when watching the lectures in 720p (see Quality Button above).

Volume / Mute Use this to set the playback volume or to mute the sound.

Simple Search
Videos that have Closed Captions available also have a search field above the chapter list. Entering a word or phrase in this field will search caption text and chapter names for the current video.

The returned results are bolded and organized by chapter. Only the chapters and text containing your search term are displayed. Clicking the results below the chapter title will position the player 5 seconds before your search term is mentioned in the video. Or you can click the chapter title to watch from the beginning of that chapter.

Clicking "Clear Results" will reset the chapters back to the initial chapter list.

Custom Start and End Points (Not supported on mobile devices)
You can specify a custom start time or chapter by adding it to the URL. Additionally, you can specify a custom end time or chapter.

Examples:
media.hhmi.org/hl/09Lect1.html?start=ch3
media.hhmi.org/hl/09Lect1.html?start=ch2&end=ch3
media.hhmi.org/hl/09Lect2.html?start=0:52&end=1:56
media.hhmi.org/hl/08Lect1.html?start=ch3&end=4:38