Hey Alex, thanks for the answer! 
what would be the benefit of swapping the time dimension and num_channels?
The 3d Conv. will be applied along the dim=1 if it is a 5D Vector, so if I swap it the “time” dimension I want to reduce, it would not be effected? Or did I get you wrong?
Could you explain what you mean with stride over time? Do you mean the stride size?