Walking_Lower_Body_S1.mov
When I look at this short clip with QuicktimeX on my desktop all I see is the brown ground, black background, and green line around the model. Why it displays correctly when I view it on line is way beyond my simple understanding.
That one is in Animation Codec again with an alpha channel, possibly because it was rendered with "Millions +".
i see brown ground, green sky and the walker model.
Choose a different codec in your render settings under Format>Save Options>Set