Displaying a specific post in a wp query by post id

I’m simply trying to display a specific post id from my custom post type ‘homepage_video’. I’m sure that this is the correct code but it seems to be returning all of the posts rather than just Post Id 40.

<?php
                    query_posts('post_id=40&post_type=homepage_video');
                    while (have_posts()): the_post(); ?>
                        <div id="video-panel-blue">
                            <?php get_custom_field('home-video-iframe', TRUE); ?>
                        </div>
                    <?php endwhile; ?>

Thanks

post_id is not a valid argument for query_post Change post_id to p,
so you get:

query_posts('p=40&post_type=homepage_video');
while (have_posts()): the_post(); ?>
    <div id="video-panel-blue">
    <?php get_custom_field('home-video-iframe', TRUE); ?>
    </div>
<?php endwhile; ?>

to see the list of arguments you can use with query_posts take a look at this codex entry