If you have found that a video in your playable is not producing audio when testing it in the browser, this will likely be due to a browser feature which stops audio from playing randomly without the user interacting.
For video audio to be heard, the screen needs to be tapped when the video is first played, or at some point when the video is playing.
How to workaround this via code
If your video needs to be played when the user isn't tapping, you can instead
Play() the video at some point when user does tap the screen, perhaps when the playable first starts, and then call
Pause() immediately after.
Then once the video is ready to play, you can resume by calling
Play() again. The video component game object does not need to be active for this to work