[Antonio Cerro]

May be it is too late to answer this question,
but it could help to another person,
I did this duplicating the element3d layer, changing colors to the copy
and applying a mask to each layer.
To apply a mask to a element3d layer you should create a new layer, apply the mask to it and change the track matte of the element3d layer.
I hope this should be helpful to anyone.
Regards.

[Antonio Cerro]

I had the same problem this morning, I realized that the .mov files weren´t aloud to open with quicktime as default, so I changed it (right mouse button/open with/choose default program).
It worked for me.