@Eosin I was working on a transparent video plugin that I was using myself and planning to clean up and release, but you beat me to the punch in a serious way, lol.
I had found a workaround for capturing the clothing transparency by using the difference between rendering on a white background...
A greenscreen is what most people are familiar with and is useful for keying out with video, so I put that front and center. But really with image editing you want to do a more neutral color to reduce the color bleed over. Black or white depending on the situation, and using selection thresholds...
kuler submitted a new resource:
Greenscreen and Other Assorted Colors - Solid-color backdrops useful for keying out transparent images
Read more about this resource...
If the texture is a bit scrunched, that's just how it is for now. However it sounds like you're seeing something like the pic below, if so make sure your smooth passes is set to 1 or above.