Horst is known for directing several award winning productions, often for children and teenagers. Her TV series De Daltons (The Daltons) was nominated for an Emmy Award and won the international Prix Jeunesse Award. Together with Sesamstraat executive editor Ajé Boschhuizen she worked on several episodes of the annual TV series Sinterklaasjournaal. This is a scripted "news program" for children, revolving around Sinterklaas. A lot of Sesamstraat crew and cast members worked on this show over the years, including Aart Staartjes and Rik Hoogendoorn.