This actually sounds a lot like me but only some of the time; I think it's related to my mood swings, which I mention in the video (beginning at 1:05:57). During the video, I was definitely somewhere in the "tired" phase of my mood swings, which I guess is part of the reason why I came off really dry and dispassionate.
I moved back and forth across the timestamps to pick up on variations, but your mannerisms and energy levels were consistent. Put differently, I am not questioning your bubbly side, it's definitely there, I just didn't see it that strongly in the clip.
Regarding your mood swings, however, your description--unstable energy levels, variable motivation, shifting from highs and lows--fits with the melancholic temperament (introverted judging) rather than the sanguine (extraverted perceiving). There are, of course, melancholic-sanguine hybrids just as there are ambiverts, although I miss the rashness I would have expected of a sanguine temperament (such as my own).
Yea, I've heard that this is a common trait for INFPs, but I can't relate to it, which I guess is one of the reasons I've been having such a hard time figuring out which type best fits me. I'm kind of opinionated, and if I have the energy for it, I sometimes initiate debates voluntarily. I guess for me, while I have mentioned that it can be tiring to debate people sometimes (especially if it's about particularly sensitive topics where I have to be more careful with what I say), it's a great opportunity for me to expand my knowledge and gain new insights on various topics.
INFPs enjoy debating insofar as they're sharing their outlook (Fi/Te). But it primarily happens in accordance with the caveat you raised, that is, if their energy or motivation allows for it. In other words, the one big struggle for INFPs (and INTPs) is to figure out strategies to expand their comfort zone, so that they simultaneously can generate new, exciting experiences (new places, new faces).
As an ENFP, my stress function is Si, highlighting internalized experience and memories that I am consistently overlooking and unconsciously pushing aside. When I de-stress, I sit down and write, doing my utmost to assemble that big jumble of overlooked sensations, channeling them through a worthy medium. In other words, the process here is reversed. The place where I face my inner experiences is the fearful step outside of my comfort zone.
These two distinctions, inside-out versus outside-in, will hopefully make it easier for you to identify which one is the likelier outlook.
I'm not sure how important of a point that is, though, because one can be a certain type without relating to all of the type's general descriptions.
I'd nonetheless say it's important, as the four functions in the stack are all conscious, albeit in a descending order. The functions also express
tandem features, which could be worth considering.