Hi Nathalie,
I am a little confused by what you are asking with regard to the Workout Blender and a web browser. Since the two are mutually exclusive of one another, I am not sure what is not working correctly. The Workout Blender runs as a separate application and does not require a browser (such as Firefox or Chrome), except to initially download the video files after purchasing them. Is there any way you could walk me through the process that you are experiencing problems with and I will see if I can recreate it here? Thanks!