Short answer, twitter is probably blocked for you. There's two ways on the message board to post tweets. One is just to post the link by itself...which is what David always does. If twitter is blocked for you, you'll see "loading tweet" when someone posts a tweet that way. The other way someone can post a tweet is to use the tweet brackets. When they do this, you'll see the tweet in a text format (you won't see any pics though). When I'm at work during the day, and I see someone post it the first way, I'll try to edit the post to put in the brackets, for my own personal benefit, as seeing the text is better than seeing "loading tweet", obviously. But when I'm at home, or on my phone, I don't think about it, cuz the tweets load just fine.