Actually it's quite easy to rotate the camera after you have imported it, even if there are lots of keyframes:
open the animation panel, go to the Y rotation of your camera (double click on the green Y), drag a marquee around all keyframes to select them, go top the bottom of the page, type in "180" where the 100 is, and hit the button next to it on the right side and choose "move by value". And voilà, the camera orientation is rotated by 180° for the whole animation.