A Problem with Marching

[Viktor]

I notice in one of my NVA videos "The vanishing Army" I think its called, in early footage ( 1956) that some DDR organs marched( Parade Step) with arms at their sides and most swung their arms normally, any ideas?. the soviets also did this .
Thanks.

[Kozlov]

Which ones were different?

Could it be a thing like "light infantry" in the British Army?

[Viktor]

Not sure, anyone any ideas?.