This is an issue for me too.
Aspect ratio modifier needed in the player.
If I want to watch flat side by side 3d video, it has to be the double of normal resolution.
If the original sbs 3d video resolution is 19201080 (9601080 each eye) it is compressed in width which is normal.
If i select sbs flat in the player, the 3d works, but the movie is still compressed in width and remains in 4:3 ratio.
It worked a few versions before, but now it works only, if the sbs video is 32:9 in ratio. It requires a 16:9 left, and a 16:9 right image to work properly.
Please fix this issue.