Kurzgesagt vid goes into some specific and recent research about how our body uses calories, but the idea that exercise can't help much with weight loss seemed obvious to me just by looking at the numbers.

A brisk pace on a treadmill will burn 260 calories per hour. At a fast pace--which most people wouldn't be able to keep up for an hour when starting out--it's 680 calories. Meanwhile, a single 12oz can of Mountain Dew is 170 calories; simply cutting one can of soda out gets you more than halfway to a decent hour's workout.

As the vid also states (and is supposedly to be covered more in an upcoming part 2), there are other benefits to exercise, but burning more calories that way is a fool's errand.