Its blank because he is set to fully private. You can make it show what ever you want. You can make it hide photo's/wall comments/videos, etc by default.
You'll have to add them to get the profile to open up, and thats if they make you fully able to view everything.
I've made some of my "friends" on facebook unable to view videos, whilst the rest can for example. You can set this kind of thing in privacy options