This shortcode will reference a media item, configurable via attributes. Using a shortcode is more flexible and won't require database search/replace when migrating domains. Core would benefit from utilizing this system rather than inserting absolute paths to media URLs. A shortcode would keep media references relative to the site's domain.

media_shortcode.php

<?php
/*
 * Plugin Name: Media Shortcode
 * Author: developdaly
 * Version: 1.0
 * Description: This shortcode will reference a media item, configurable via attributes. Using a shortcode is more flexible and won't require database search/replace when migrating domains.
 * 
 * ex. [media id="97"] = <img src="http://example.com/97-300x150.jpg" class="thumbnail">
 * 
*/
 
add_shortcode( 'media', 'shortcode_media' );
add_filter( 'image_send_to_editor', 'shortcode_media_send_to_editor', 10, 7);

function shortcode_media_send_to_editor($html, $id, $alt, $title, $align, $url, $size ) {
	$url = wp_get_attachment_url($id); // Grab the current image URL
	$html = '[media id="' . $id .  '" alt="' . $alt .  '" title="' . $title .  '" classes="' . $align .  '" size="' . $size .  '"]';
	return $html;
}
   
function shortcode_media( $atts ) {
	extract( shortcode_atts( array(
       		'id'		=> false,
		'size'		=> 'medium',
		'classes'	=> 'thumbnail',
		'icon'		=> false,
		'permalink'	=> false
	), $atts ) );
 
		
	// Get mime type
	$type = get_post_mime_type( "{$id}" );
	switch ( $type ) {
		case 'image/jpeg' || 'image/png' || 'image/gif':
			$image = wp_get_attachment_image_src( "{$id}", "{$size}", "{$classes}", "{$icon}" );
 
			$before = '';
			$after = '';
			
			if( "{$permalink}" == true ) {
				$before = '<a href="'. wp_get_attachment_url( "{$id}" ) .'" rel="attachment wp-att-'. "{$id}" .'">';
				$after = '</a>';
			}
			
			$output = $before .'<img src="'. $image[0] .'" height="'. $image[2] .'" width="'. $image[1] .'" class="'. "{$classes}" .'">'. $after;
			
			break;
		case 'video/mpeg':
		case 'video/mp4': 
		case 'video/quicktime':
			return $base . "video.mov"; break;
		case 'text/csv':
		case 'text/plain': 
		case 'text/xml':
			return $base . "text.txt"; break;
		default:
			return $base . "file.file";
  }
	
	return $output;
}

This works great. Thanks!