An experimental procedure allowing full-field measurements during dynamic crack propagation in membranes under large strain is presented. It consists in a two-camera set-up in order to perform digital image correlation during both quasi-static loading and dynamic fracture of the sample. Tested with a highly stretchable polyurethane, this technique permits to retrieve the material configurations of the sample all along crack growth, which is a crucial step toward a complete mechanical analysis of the problem. The dynamic formulation of the J-integral can be computed and its contributions are analysed: the roles of kinetic energy, stress power and strain energy density in the membrane are compared. The applicability of this approach in the case of high speed crack growth is then discussed.