Hi Thorsten. The intellectual property of the Space Quest series (and Sierra as a whole) is in the hands of Activision-Blizzard. It is no longer owned by Ken and Roberta Williams who built the Sierra Gamers site to stay in touch with the fanbase.
That being said, I see no problem using Sierra images in videos and posting them on Youtube if there is no financial gain involved. Lots of fans, including myself, have lirerally uploaded thousands of Sierra videos.
