function streamtube_filter_player_container( $player, $setup ){
    return sprintf(
        '<div class="consent-container position-absolute start-0 top-0 w-100 h-100">%s</div>',
        $player
    );
}
add_filter( 'streamtube/player/file/output', 'streamtube_filter_player_container', 2,2 );

function streamtube_add_custom_css(){
    ?>
    <style type="text/css">
    .consent-container .videojs-streamtube{
        position: absolute;
        top:0;
        left:0;
        width: 100%;
        height: 100%;
    }
    </style>
    <?php
}
add_action( 'wp_footer', 'streamtube_add_custom_css' );