Hi,

I am searching for a way see my video in my K2 item above my item picture... I have changed an item.php, but probably the wrong one.

So I am asking you guys - what can I do :)

you can See my Article here: theworldsartgallery.com/

Thanks a lot for your time!

You need to read this post about template overrides.
getk2.org/documentation/tutorials/174-templating-with-k2-and-the-concepts-of-sub-templates

This one is useful if you are using multiple templates.
nuevvo.com/blog/item/84-k2-inheritance-sub-templating