There's some "new" research about calories and the human body that has been making the rounds lately. This research suggests that individuals are predisposed to burning a set amount of calories, somewhat independent of activity level. It also takes something crazy to alter that, and probably for only a short time. For ex, a coach potato uses 2000Cal a day. Then they take up marathon training and will likely burn far more... but not permanently. Eventually, the now marathon runner will return to burning around 2000Cal a day again.
This vid uses a lot of fudge-factor words - "about", "approximately", etc. It would be difficult to know how much wiggle room there is in all of those, especially for an individual person. Remember that when thinking about these concepts for yourself.
A concept in this vid that I haven't seen is that extra calories can cause inflammation because your immune system is acting too strong. Interesting.