Videos have no sound?

I’m testing the first video “Into the wild: Sembawang Hot Spring Park” in your link and I see there is no audio in the video itself. Only the first frame has a bell like sound.

But, I can guess the issue. Due to the recent browser restrictions, when you load the video page directly, the audio is disabled by default to keep the video autoplay work. So, you may need to manually unmute the audio from the player controls.

Kindly try disabling the “autoplay” feature.

Autoplay and Browser Policies
Chrome: https://developers.google.com/web/updates/2017/09/autoplay-policy-changes
Firefox: https://blog.mozilla.org/firefox/block-autoplay/