I am new to blender and I tried to animate a camera path following this tutorial: https://www.youtube.com/watch?v=vasfFsxCsAE
The author creates a NurbsPath for camera to follow and an empty to specify the focal point. However, things don't go to plan for me. First, after inserting the path and making the camera follow it, I use Ctrl+A to apply location, rot and scale, as recommended at 6:33, but I get a "Objects have no data to transform" message. I don't know which effect it will have on the animation, but it doesn't seem good.
Also, during the animation the camera is often diagonal to the ground, I also tried to use Twisting->Z-up for the NurbsPath as suggested at 5:50, which doesn't have the effect I expected, the camera still stays diagonal. Then I tried to add "Limit rotation" constraint to the camera. Now it stays parallel to ground plane, but instead flips 180 half way through the path and then flips back.
Additionally, when I add an empty, move it to the point I want and do Ctrl+A to apply the location as suggested at 7:07 my empty actually moves to a different location, which doesn't happen in the video. So it looks like something is wrong with my coordinate system.
Could anyone help me to resolve these issues?
The file is here, I got the model from blendswap.com, it is made by aXel.