Learners in the process of developing complex skills need a rich mental model of what such skills entail. Textual analytics rubrics (TR) are a widely used instrument to support formative assessment of complex skills, supporting feedback, reflection, and thus mental model development of complex skills. However, the textual nature of a rubric limits the possibility to deliver contextual and dynamic (time-and behaviour-oriented) information. In the Viewbrics online tool, we developed a version supporting the delivery of contextual and dynamic information by adding video-modelling examples with embedded self-explanation prompts to textual analytics rubrics. We called this combination as video-enhanced rubrics (VERs). Our current study investigates whether the Viewbrics online tool supports complex skills development and whether either textual- or video-enhanced rubrics best support complex skills' mastery. The study was a three-group (VERS n = 49, TR n = 54, control n = 50) within-subjects design. Learners' performance of complex skills was measured through expert, peer, and self-assessment using the Viewbrics online tool. A multilevel regression analysis shows learners in the TR and VERS conditions consistently outperforming the control condition to varying degrees across skills. However, no differences have been found between the two experimental conditions. Positive results across different complex skills indicate the Viewbrics online tool can be used to support the development of a wide range of complex skills in secondary education.