As a fan of BluffTitler (also !) I have been confronted with the use of video files supposed to contain an alpha chanel.
It's clear that ProShow can't handle these kinds of file so we have to go around !
There are 2 ways of solving this case :
1- create an alpha chanel of the animation in BluffTitler. First, export the animation in its normal status with the name show.avi for example. Then we must create an alpha chanel. This may be done by giving the ambient light a value of 255, 255, 255 which is the white colour. Once it's done, you may export the video with the name show_alpha.avi for example. In ProShow, import both video files, the show_alpha.avi as layer 1, show.avi as layer 2 and your background image as layer 3. Give layer 1 the status of masking layer. And voila !
2- import the show.avi file in ProShow and apply a chroma key on the background color of the animation (generally it's black) using the intensity sliders. A value of 10% on both intensity sliders should be fine.
You may download a file containing both AVI video examples plus an explanation. It's in French but the main interest is in the files for your tests.
http://jeeep.breizhbleu.com/Atelier/BT.zip