During teacher training, is it possible to rush professional experience? And if yes, how can teacher curricula do that? Our contribution try to understand which training activity is generated when a trainee watches videotapes showing professional teachers at work and why this activity can be formative. We collected videos of trainees surfing on the website Neopass@ction (http://neo.ens-lyon.fr) (Ria & Leblanc, 2011). Trainees watch 1) films showing teachers (novices) at work, 2) films bringing one teacher face to face with its own work, 3) films showing others novices and experienced teachers commenting teachers (novices) work. Through these videotapes, we try to understand why looking at teachers at work and talking about it can be formative for trainees. To analyse this training activity, we refer to Peirce’s Semiotics (1978). We analyse the signs produced by trainees when they are looking and commenting the films (Lussi Borer & Muller, to be published). According to Peirce’s Semiotics, this signs reveal the process of deconstruction-reconstruction of the meaning of the activity viewed and also the process of deconstruction-reconstruction of the meaning of the viewer’s own activity. These processes seems to be formative because they generate professional experience vicariously.