Is there an hook to modify programmatically the thumbnail shown from the video module? I'm using the video module and i need to show a different thumbnail if the user who is watching the node is a guest or a logged on user (if the user is a guest i want to display a standard thumbnail). Is there an hook to do this?
you could just modify the template to show a different thumbnail for anonymous users. You can use the Theme Developer module to find the right template to modify.