Auto selection of category based on subject line or TAG

I doubt there are any plugins out there that can do what you want “out-of-the-box”, however you could probably write a plugin to do what you’re looking for. Some basic boilerplate logic could look like

function jcharnock_insert_post_category( $post_id, $post, $update ) {
    // Only run on inserts.
    if ( $update ) {
        return;
    }

    $title_categories = array(
        'video',
        'image',
    );

    // See if the category is the first word in the title, use a delimiter for safety.
    foreach ( $title_categories as $cat ) {
        if ( 0 === stripos( $post->post_title, "{$cat} - " ) ) {
            wp_set_object_terms( $post_id, $cat, 'category', false );
        }
    }
}

add_action( 'wp_insert_post', 'jcharnock_insert_post_category', 10, 3 );

What does this do?

With this action in place, if you were to send a post to your site named “Video – My new cool video post” or “Image – Some image post”, the new posts would be assigned the respective category of ‘video’ or ‘image’.

Title categories are delimited with a - (space-dash-space) so that other posts don’t accidentally get miscategorized, such as “Video players that are awesome” or “Image software reviews”.Of course, you can make that delimiter whatever you want, or not use it at all, it’s just to help minimize mistakes.