I first thought INFP because of the sad feel, especially in the beginning (her sitting down in front of the tree and then putting her head down, Also, innocent child in the forest looking taking tentative steps, seems wary). In the orange-tinged part Sarah closes her eyes, as if to concentrate more on "taking in the moment", feeling the emotion to its full intensity (Fi?).
The blue-tinged part seems to make us want to see "loneliness", but as she "transforms" into her orange-tinged self (the mud-washing off part), she seems less defeated, shows less little-lost-pensive-girl-in-the-woods and more valiant-woman-on-a-mission-who-has-been-reborn-and-ready-to-fight. Perhaps an INFP would remain defeated, so that if the video was INFP, the whole video would be shot in blue? The orange parts seems more INFJ. Also the part where Sarah is staring intensely to the side of the camera in her portrait shot. INFPs aren't that focussed, INFJs are more likely to have that "I've got a mission" look.
But this lyrics makes me think "warrior"/"proactive stance" and thus INFJ: "No more compromise"
INFJs are called "an inspiration to others": "I am the spark"
INFJs value authenticity and exude integrity. Staying true to themselves is paramount. Sometimes they can be uncaring how they come off to others (I can provide links to where I've read this): "Don't want no cheap disguise"
Defiance, perserverance in the face of adversity, not giving up to soon, tenacity:
"I will stare into the sun until its light doesn't blind me
I will walk into the fire until its heat doesn't burn me
And I will feed the fire"
INFJs are often cited amongst the types with the highest GPAs in school. They keep working and working on promoting their cause/movement/activist endeavor (J-type).
The lyrics don't say, "I will stare into the sun but as soon as it starts blinding me I'm going to give up, I'm not going to wait until it stops blinding me, I'm too impatient." or "I'm too lazy to feed the fire, I'm going to let someone else feed it". INFPs are dead last in a list of income/salary, even though they are either third or fourth for highest IQ.
Though this line strikes me as INFP: "You I see as my security". INFPs are wussier than INFJs. INFJs don't need someone to act as their security blanket as much as an INFP would. INFJs aren't as vulnerable.
"I yearn for comfort" - INFPs are called "emo" and I saw one motivational poster that had "my soul is wounded" written on it for INFP, though I also saw a lot of posters for INFJ with the whole "I am hurting" business.
I think the lyrics are more N than S because they are metaphors rather than actual actions. I don't think she literally wants to make throw some gasoline on a fire. She's using "feed to fire" to refer to increase the intesity of sometime else. Perhaps her own motivation, or her own competitiveness? When she says "teach me to walk again", I don't think she actually forgot how to walk, she's using it as a metaphor to mean to stop being defeated, to go back to her old self who was more the self she wants to be now. I'm guessing her old self was more self-sufficient, more viable, more effective in the world? A human can't literally be a spark; it's impossible according to the laws of physics. "Spark" is just a metaphorical term to mean a change-maker or a charismatic person or an effective person who gets a lot of stuff done.
I also don't think it's an ISFJ video because it's got a very arty, avant-garde feel to it (she's nude covered in mud, fer chrissakes), and I've looked at the Youtube motivational poster video and it seems like ISFJs are very conservative traditionalists, not into all this new-agey hair-whipping stuff