He red carded a Scottish lock. Wales had a player sin binned but he's back now. We have 45 minutes of rugby where the Scots have 14 players and the Welsh have 15.
The ref is a kiwi - not really his fault though. The rule book says red card.
I don't think it was necessary though, he was cynically tackled without the ball and he lashed out without looking. His boots caught his tackler in the head (who incidentally was yellow carded as well) so therefore it has to be a red.
Nearly 50 minutes of rugby one man down and the Scots kept running the ball and attacking. They've played with great heart I reckon and deserve the last two tries.