We wanted to try compositing basic 3D VFX in the background with GH4 4K video (inspired by videogames I used to write). I used 3DS Max to create a simple scene with an alpha channel and tried to composite everything in Premiere Pro CC. Unfortunately, PPro (and AE) have issues with the 3DSMax alpha channel (not a premultiplied color issue) and the low levels of the alpha channel appear to get clipped, cutting off subtle glows, etc., making correct compositing impossible. So I moved the background plate into 3DS Max and rendered the 3D elements directly on top. I had originally planned for a much more complex 3D scene, including having objects come out of the background and go around her head, but the time spent trying to work around the compositing issue took too much time.
http://youtu.be/wDtryeCtkWM?t=4m15s (link jumps straight to VFX shot)
http://youtu.be/wDtryeCtkWM?t=4m15s (link jumps straight to VFX shot)