Hi @Bartex_1
First you have to own the Beyond The Baltic Sera DLC, in order to by a HTC trailer
Second you need to save edit the trailer, I use TS SaveEditor Toll to decrypt the savefile.
When you have decrypted the file, you can open it in Notepad, then you have to search for Country_validity, and change the number to 0, and delete the country that is listed under.