Allows to upload particular filetypes in particular page using rtmedia_uploader source code

function.php

function rtmedia_media_uploader_attributes_shortcode( $attr ) {
	global $rtmedia;
	$allowed_media_type = $rtmedia->allowed_types;
	/* page id */
	$page_id = '95';

	/* File extension */
	$extn = 'doc';
	if ( get_the_ID() == $page_id ) {
		$extn = explode( ',', $extn );
		if ( isset( $attr['media_type'] ) ) {
			if ( isset( $allowed_media_type[ $attr['media_type'] ] ) ) {
				$allowed_media_type[ $attr['media_type'] ]['extn'] = $extn;
				wp_localize_script( 'rtmedia-backbone', 'rtmedia_upload_type_filter', $allowed_media_type[ $attr['media_type'] ]['extn'] );
			}
		}
	}

	return $attr;
}

add_filter( 'rtmedia_media_uploader_attributes', 'rtmedia_media_uploader_attributes_shortcode', 10, 1 );