you do not need a part 107 license to livestream a drone flight. not even once is there any mention of the word "profit" in the faa laws. either you are flying for fun...or you are you are not flying for fun. if you are not flying for fun, you need a part 107. it's really that simple. in general, it would be helpful to think about having a part 107 in furtherance of a business. any discussion about platforms or techniques or methods or advertising, etc is irrelevant. none of that is mentioned in faa laws, it is only made up by people who want to take a shot at interpreting what they think the law means. I agree there has been casual commentary by the faa from time to time but I would refer you to what they have legally done rather than what they may have said.
I know I will get a lot of pushback on this. there will be people who will swear that anyone who is posting a video on YouTube without a part 107 is breaking the law and the only reason why the faa is not going after them is because there are too many for the faa to handle or they have to get a complaint first or the faa is "looking the other way" but it's still illegal or some other similar nonsense. but in reality, it is because the faa is unable to prove a person's intent when the flight took off. that's it, bottom line. when they have enough information that you are not flying for fun and you don't have a part 107, they take action.