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.
For example:
If the original sbs 3d video resolution is 19201080 (9601080 each eye) it is compressed in width which is normal.
BUT
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.