Binding Darkness

[Amaurot]

Sorry for my poor English, but I just cant grasp the meaning of this spell.

Binding Darkness (Sp) from illusion (shadow) school of wizard:
"...a creature entangled by your shadows has concealment from those without darkvision or the ability to see in darkness, and other creatures likewise have concealment relative to it..."

Does that mean the entangled creature is considered concealed from others who don't have darkvision, and, on the opposite, others are considered concealed from the entangled creature?

What are the "other creatures likewise"? Other creatures who have darkvision? Or any other creatures?

And what if the entangled creature has darkvision?

[zza ni]

he has concealment from anyone who look at him without any ability to see in darkness. and anyone he looks at has the same if he ahs no ability to see in darkness(think of it as a screen betwin him and anyone else that seeing in darkness pierce.)