Can you hear sound when you don't use chrome? e.g. via Winamp or any other music/video player?
Depending on what embedded software is being used to play the videos, try right-mouse clicking on the video and seeing if there is a Settings or Options button. If there is, check the audio set-up....you might be able to change it here.
Also, check the Playback Device setting via right-clicking the speaker icon at the bottom-right of your screen (taskbar)