The vet told us 2 weeks after surgery that Roxy can start playing (we chose to wait 3-4 weeks). She ends up coughing as soon as we start to tug-a-war with her. Because of that cough we put the toy away. We will of course show this video to her vet to see if it's ok for her to cough a little or if we should keep taking the toy away. When I find out I will put an update in this video description.
*UPDATE* 12-19-11
Vet Called today and told us that amount of coughing during play time is ok. As we know Roxy will always have a cough. I think we tend to over react on her coughing (I'd rather over react then not react at all)