What I feel is that these sorts of demonstrations are very useful in instigating change and motivating others to seek change as well - but only in the sense that there were people out there who cared enough to protest. However, this can be said for people who accomplished the same goals in more effective and respectful ways. I can't speak for what impact this sort of thing will really have, but I think protesting for this sort of thing, in this instance, seems futile. At least for the present.
They're picketing some Chic-Fil-A franchise, owned by someone who's basically irrelevant to what the company owners have said outside of their business relationship. That someone is just there to make money, not further his/her agenda. Unless the owner is privately motivated by his/her goals, feels like it's not worth it to continue their operation because of these protesters (which does not really help accomplish the main objective), or zombies attack, I don't think anything's gonna change here.
I don't think protests like these won't have an impact on the history of the gay rights movement. I think it will be another instance through which people will slowly but surely integrate teh gayness into their mental schema. That's why I think it's good in the long run. But I'm not a fan, because the video is of a bunch of self-righteous hotheads who think that screaming at the top of their lungs will convince the manager to shut their franchise down. Tbh, my thoughts were that the protesters sounded crazy and the priest was being a presumptuous douche. That being said, I think there are more intelligent and effective ways to advocate against discrimination.
It's not my style.