Depth Only Clear Flag Camera Issue

Hi everybody,
I am trying to play the turnaround of my character without viewing the skybox in the player. I found different threads about this issue so I put two camera with different depth, and different clear flag (depth only and skybox). When I play the animation my character leaves a trail and the exported movie (with AVPro Movie Capture) doesn´t get any alpha data.

I have tried everything I found in the past threads, but the trail is still there. I have tried to put even a third camera to solid color with black alpha, but it didn´t work. The movie is exported with a black background without any alpha information. In unity 4 it worked perfectly, so there is anyone that could help me to understand how can I set the clear flag to depth only without the trail issue?

Thanks everybody, that´s my first threads, hope to pst it in the right place.
Cheers,
Daniele