How to get 1080 HD videos from itunes?
Glad to see you know about those settings because they are a bit hidden in my opinion. To answer your question, the music videos are in the quality they were published by Sony Music Entertainment (in this case). Music videos haven't gotten the same amount of TLC like films and TV shows. In music videos, video quality hasn't taken a priority as much as sound quality so most companies decide that it is important for a lot of music videos to fit on a devices as fewer high definition videos. Looks like most music videos are standard definition (sub 720p) and it will probably stay that way until 16 GB devices go out of style.

Who knows, maybe by then there will be a simple option to download HD versions of previously purchased music videos. Sorry for the bad news but I wanted you to know that you aren't doing anything wrong.