img bbcode works just with this formats: .jpg, .jpeg, .gif, .png, .bmp.
the reason why phpfusion doesen't allow that url to work. is to protect you from hack attempts.
But i will look more into this problem and try to find a way, because i saw some forums, that allow this type of url images.
Till then, you should search for a new image hosting.
I will give you a list.
imageshack
photobucket
tinypic