I saw your tutorial on the BT site. You should post this in Vegas as well, or at least a link. Well done!
Other than using alpha channel transparency, you can make the background green and use chromakey to make it transparent, and thus export to mp4 rather than avi. Depends on what you're doing.
For those who don't know what BluffTitler does, here is the description on the BT site:
"BluffTitler is a Windows desktop app for creating intro videos
Want to impress your family, friends and clients with spectacular 3D titles and intros? But do not want to use complex and expensive 3D animation software? BluffTitler makes it easy and affordable to add 3D effects to your videos!"
The program is very detailed and powerful. It comes with many, many, working examples. You can buy Template packages and use them as is, just replacing text and images/video clips, or use the components and/or modify as you wish. Understanding how everything works, however, takes a lot of learning and practice.
There are a couple of other programs that support constructing certain things for BT, like Bixangelo, a 3D program. At its simplest, you can handwrite your name as a line, and then use the eps file in BT and have your name handwritten as you wish - colour, effects, speed, etc.
BT itself works with a camera (or up to 4 cameras) that can move about a 3D scene, or the scene can move about a camera, or both.