This could possibly be a reverse sneeze. This can happen with any irritation of the back of the throat. There is usually no treatment recommended - but it is sometimes associated with allergies. Benadryl at 1mg per pound of body weight twice daily can be recommended in these cases. Here are links to more information and video clips of other dogs reverse sneezing so you can compare what you are seeing.
Heart problems can certainly cause coughing. Coughing after waking up or after exercise or excitement can be indicative of a heart problem. They are often also a bit lethargic and not as active as previously. They may also have some labored breathing associated with the intolerance to exercise. If the dog is acting fine in all other aspects, and it happens in little fits like the reverse sneeze than it is more likely to be this. However, if this happens in conjunction with exercise, or isn't in little fits like seen in the video, I would have the dog examined to make sure there is not some other problem going on. If she has not had a heartworm test or been on heartworm preventative regularly I would make sure this was done as well. Here is a link to more information.