When I press tutorial button this is what I see on screen (screenshot).

Please note the timer - it points at 0:21 already (I think it should be at 0:00?)
When I now press "play" button I can hear sound/voice but no visuals - even timer doesn't move forward.
When I press "close" ("zamknij") button I can hear "click" sound but nothing happens so I am stuck at this screen. :(

Something is not right I suppose? Anyone else has similar experiences?

Exactly the same problem here - but on Vista 64... is there a codec-problem or something?

I am having the same issue on Windows 10 using the Microsoft Surface Pro 4. None of the tutorial videos have image.

Problem appears to be due to tutorial videos are demuxed into separate files for audio and video.
And using Ogg Vorbis on top of that.

If not working properly in game best bet is to watch them from the installation folder.
Will need a program such as MPClassic to play them. (The Swiss Army knife of media players)
Even VLC doesn't support this type properly.

[Installation Folder]\The Witcher Adventure Game\TheWitcherAdventureGame_Data\StreamingAssets

**UPDATE**
Problem is this exact version of Visual C++ Redistributable needs to be installed.
Visual Studio 2012
Even if you have newer version already installed the 2012 version is still required.

https://www.microsoft.com/en-us/download/details.aspx?id=30679