Stop! Stop! You will make your site supper slow / can be banned on reddit (if that ever be posible).
- You can try to use save_post and filter your post_post content body.
- You can setup it a crop scheldules to parse your post’s.
as for your code… Read about get_post_meta last optional attribute there is difference in return if you will use that last attribute. Thats can be a problem isn’t it?