Lol - "these birds flush so fast." I'm not sure if the grouse in the Northeastern US are from a different genetic stock than in Northwestern ON, but around here the ruffies and sprucies are dumb as a sack of wet hammers. Basically, they just stand there on the trail or clearing and wait for you to shoot them. Maybe, you might pop one up out of the tall grass, and if you miss it on the wing, it'll just wait for you wherever it lands.
Occasionally though, you'll come across a wiley one, especially early in the season, and you might actually get your boots dirty going after it. Those ones are fun.
All the dog does for me, is heel on the trail and go retrieve the dead bird. His reward is a fresh, warm heart and liver, and he's one happy dog!
Good video - I like watching hunting dogs work.