To watch video(s) of the talk, make a choice from the video menu (at left). You will need a player for the desired format (and speakers, a soundcard, operating system drivers, etc.). More help is available.
To listen to audio of the entire talk, make a choice from the sound menu (at left). Otherwise, select a section from the pictures menu and you will be offered the audio that goes with it (if available). You will need a player for the desired format (and speakers, a soundcard, operating system drivers, etc.). More help is available.