Changing Text based on Text Domain

add_filter( 'gettext_streamtube-core', function( $translation, $text, $domain ){

    if( $text == 'Add From Source' ){
        $translation = 'Embed';
    }

    return $translation;

}, 10, 3 );

add_filter( 'gettext_streamtube', function( $translation, $text, $domain ){

    if( $text == 'Sign In' ){
        $translation = 'Sign In/Up';
    }

    return $translation;

}, 10, 3 );