A Media Placeholder should be muted in most cases, unless you are creating a template where you specifically want the user’s uploaded video to be heard.
make sure it’s set to mute in the toolbar. (The speaker icon should have a diagonal line across it).
Screenshots
2. Media Fit/Zoom
A Media Placeholder should be set to Zoom, in most cases.Uncheck this box only if you are creating a template where you specifically want the uploaded video to fit instead.