I'm confused about what this means when for example I want the video to play via javascript external to the embedded player. For example, when user clicks text

I'm confused about what this means when for example I want the video to play via javascript external to the embedded player. For example, when user clicks text link on page that opens a lightbox (such as fancybox) containing an embedded video. I (and the user) would want the video to begin playing immediately upon opening the lightbox. But it sounds ilke the user will now need to additionally press play on the embedded video? Anyone know? I really hope this is not the case. I'm hoping the clicking of the initial text link that opens lightbox is enough to authorize video playback with sound on all devices.