Shortcode Function – Can’t get anything else to return after running shortcode within shortcode

You shouldn’t call return twice in a function, as it isn’t supported and only the first return is evaluated.

What you can do is assign the first do_shortcode to a variable and return the variable concatenanted to the second return.

function youtube_media_shortcode() {

    $shortcode_output = do_shortcode( '[x_video_embed no_container="true"]<iframe width="560" height="315" src="'.get_field('youtubeurl', 'option').'" frameborder="0" allowfullscreen></iframe>[/x_video_embed]' );

    return $shortcode_output . '<div class="youtube-text">'.get_field('youtubetext', 'option').'</div>';