If the bracket holes don't line up with the brick mortar joints, just use a piece of lumber to install the bracket. Screw the lumber to the horizontal mortar joints, and then screw the bracket to the lumber. If that camera doesn't weigh more than a few ounces, you can fasten the bracket to the lumber with 5/8 inch screws and that will be plenty strong enough.

Paint the top end/edge and back side of the lumber (facing the brick) with end cut preservative so that any rain water accumulated there won't cause the wood to start rotting. Allow a half hour for the end cut preservative to be absorbed, and then wipe the excess off before mounting the lumber. You can paint the rest of the wood to match the brick colour if you want.

PS:
And, if it were me, I would caulk around 3 sides of the wood (Top and both sides, leaving the bottom uncaulked) with Stone Mason Gutter and Siding Sealant sold at Home Depot in Canada (at least) to prevent rain water accumulation behind the wood. This product is made by the Henry Company, which I think also operates in the USA. If you can't get this, then an identical product is called "Kop-R-Lastic" caulk which you should be able to find locally. Kop-R-Lastic comes in 8 colours, whereas Stone Mason Gutter & Siding Sealant only comes in white and clear. Kop-R-Lastic has a larger colour choice, Stone Mason's packaging (the tube graphics) are a little more attractive, but what's inside the tubes is identical.

Stone Mason | Stone Mason Gutter & Siding | Home Depot Canada

The reason why you want to use this caulk, and nothing but this caulk, is because it's cohesive strength is even higher than it's adhesive strength, meaning that it sticks to itself even better than it sticks to most construction materials, like brick and mortar. So, if you ever want to remove that bracket, to replace it or eliminate it, you just have to get one end of the caulk started and it'll pull off the brick and mortar cleanly, just like a rubber rope. It won't leave a mark on your porous brick that's difficult to remove like other caulks will. I have 66 windows in my apartment block, and I won't use any other caulk on them except this one. If you can't get this caulk, I wouldn't use any caulk at all.