TV is a medium with high penetration rates and has been suited to deliver informal education in several aspects since years. Thus, interactive TV may play a significant role in the current Life-Long Learning challenges, provided that meaningful applications are implemented. In this research work, we have explored the added value of interactivity in digital TV, with a particular focus on Serious Games (SGs), given their growing relevance in technology-enhanced learning. We have followed an evolutionary rather than revolutionary approach, in particular given the still traditional use of TV by a large audience. The approach preserves a media-driven strategy and the role of the author/director in proposing contents (storytelling), as in the TV tradition. We argue that interactive SGs may help the viewer to better contextualize/understand the video stream and go more in depth about the touched items at the end of the stream. This also enables new iTV applications, in particular to support weaker users (i.e. users that could not view the video without a help). This paper presents the results from user tests based on an interactive enhancement of a clip from the Disney's Snow White movie, that challenged the authors in addressing a dynamic, high-value document. Qualitative and quantitative results show the potential of the system for informal education. The tests also stress the importance of good solutions (e.g., development languages, display modalities, metaphors) for synchronizing video and overlaid interactive elements. To the best of our knowledge, this research work is the first one discussing user test results about the usefulness of a class of iTV SG applications that can be instantiated serially in several different contexts.