I have a scene strip (with alpha channel) from a compositor setup, in my VSE timeline. The video clip (in the compositor) is affected by a key node that creates an alpha channel. I send this to the VSE as a Scene strip.
In the VSE I made sure to set the Compositor's Scene strip Properties>Filter>Premultiply to active. The rendered output from the VSE scene (in the UV image editor window) is correct but the VSE preview window will not refresh and show the alpha, instead it just shows the premultiplied color channels (white).

I cannot submit video with the demo .blend due to no packing function.

WinXP 32bit 2.64.9 r52376