Hello Doetze,
I'm not sure about Kiwi,but in the linked video,peat moss is used for Blueberry seeds. Brady

Here is a link that might be useful: Growing Blueberries from seed

what kind of kiwi are you germinating?if they are kolomikta or arguta I simply spread the seeds over a damp piece of paper towel and into zip lock baggie.You need to refrigerate for several months,then around Feb/March bring them out during the day then put them back in the fridge for the night.Do this for a few weeks until you start to see them sprout,then simply pick them up with tweezers and plant in peat pellet starter trays.I will be doing some kiwi seeds very soon.If cold hardy kiwi is what you are doing, I can post pics of the progress.

Glenn