That can happen when people play your game from the app instead of the website; they register as downloaders instead. At least if I'm reading your question correctly?
No, so if you're looking at a particular games' stats at the top you can see views (which might not be browser plays) and downloads (which are plays, but not browser plays). There's a graph of browser plays per day, but I think the only way to see total browser exclusive plays is to add up each day's browser plays on the graph, can it be it's own exclusive value at the top?