The method that sets the iframe src and height (buildVideoIframe) is called on afterChange only (i.e., when the slides are navigated), so it doesn't fire on initialisation. Therefore, if the video slide/iframe is the first slide, its src value will not be set.
The method that sets the iframe src and height (
buildVideoIframe) is called onafterChangeonly (i.e., when the slides are navigated), so it doesn't fire on initialisation. Therefore, if the video slide/iframe is the first slide, itssrcvalue will not be set.