Hello.

On my page www.blekitni.com/index.php/aktualnosci/item/2837-pls-porazka-na-koniec-leopoldow-0-4-jarmolowka I added some video in media.

How to move that video "inside" article, not at the end after all information about article?

If you want to move it into a position close to the fulltext, use and override and move the itemVideo code up in the override.
If you want the video inside the content try the allvideos tags
Check the all video docs
5. Easy, descriptive syntax for media embedding - {format/provider}filename{/format/provider}. You can also use syntax like {format/provider}filename|width|height|autoplay{/format/provider} (e.g. an "autoplaying" {youtube}he73js82|600|450|1{/youtube}) to display videos at different dimensions!

Thank You

Nice one William :)