is the duct open or close

Can't really definitively tell from the outside unfortunately - those wing nuts are to tighten the damper to the duct. The opening and closing of the damper turns on axis.

usually turned inline means open, and across means closed. If it was installed correctly

Looks to be almost closed. The threaded part is oblong and goes in the same direction of the flap inside (ignore the lever in this pic.)

Just check your vent and you will know.

I think some other may have already suggested this, but perhaps I can clarify the operation.

The slot on the end of the threaded shaft indicates the direction of the damper.

You loosen the wingnut which allows you to turn the threaded shaft with a regular slotted screwdriver. Once the slot/damper is in the desired position, you hold it in that position with the screwdriver while you tighten the wingnut with your fingers to prevent movement in the future.

Look at the little notch on the bolt. It’s blurry on the video but looks like it’s open to me.