Convincing?
I'll try a second-by-second analyzation of your vid:
0:04 Boom! straight Fe smile "Hello Hello Typology Forum."
0:08 Eyebrows Up + Smile = Fe. "Um Yeah"
0:23 You are thinking for a suitable word? That could be Ni or Si. "Pontificate out loud."
0:01 - 0:29 Intermittent and significant signs of Fe. You just can't let go of that smile, can you?
0:31 - when you release the smile, it becomes Ti. "Um, so yeah."
0:31 - 0:56 - some more signs of Fe
0:57 - you are looking for information again? "I think that's true in the younger INFJ's and such." You were trying to fit it with your "Ni" and the idea fits with your perceived internal storage of ideas. Ni
1:21 - "Um.." When you release the "habit smile", It becomes Ti. You are arranging your logic.
1:31 - 1:32 - Notice when you "wrinkled" your face while trying to show a point? That's externalized emotion that's meant to influence. "I feel that INFJ's are (x) in their relationship with people."
"I'm rather not." -Because of your differing Ni. INFJ's, in general, tend to follow an Ni based on their Fe but not necessarily in reality.
If this helps, I'll continue..
(I was thinking ENFJ but yeah...seems having an Introverted demeanor.)
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For contrast
INTJ:
YouTube - Some INTJ | ENFP Differences Notice the lack of emotional expression?
1:34 "mhm" Te.
X:XX Hand gestures does not come with externalized emotion. Te.
Fi is when this guy actually shows emotions. And when he does, it will be subtle and less expressive as it is meant to be internal(for the self) not externalized.
Btw, there are many "fake INTJ's" in youtube.