That is difficult to believe. So you can earn money this way? That he doesn't use it himself may be somehow understandable. If his account is blocked, or they don't pay him, it costs him money instead of making money from it. How many seconds advantage do you have with your stream compared to a quote from a bookmaker? Average I mean. Is that enough to place a bet if you already know who scored the next point ?
Personally I do not know if what the OP is proposing is a legit offer or not, however this is a very old way to make money from casinos, I do not remember the name of the strategy but in the old days where TV was not so available a group of gamblers will join efforts and they will go and see the tennis matches themselves and take advantage of the time it took casinos to update their odds and make bets that they know they are going to win.
As you may guess casinos do not like this and eventually they are going to realize what you are doing and you will get banned, then the group will separate and recruit more people and keep doing this stuff, so it makes some kind of sense the OP is offering this as most likely he cannot take advantage of it himself, but once again I cannot vouch for the validity of the offer of the OP.