She just wanted an excuse to hug Applejack.
 
Who wouldn’t?

If anything, this is the bravest we’ve seen Fluttershy. If anything went wrong, it would have been the most traumatic and violent event she’d have ever witnessed. Despite the risks of seeing something like that, she came to watch anyway.

@Ihhh  
And not the people that do not understand the context is not the same?

@Inkan1969  

@Inkan1969  
Read the comment point out how it’s not.

Yeah, what’s the deal here? This was way off.

@gittonsxv  
@SJArt117  
@Prof.NightJack  
@Philosopher Stone  
@Background Pony #E99E  
Hmm, I never thought of it like that.
 
@Psyga315  
Trying too ha… Wait, is that ruds? I don’t know anymore@Collin Magney

Blame the storyboard artist.

Reminder that Fluttershy refered to S1 manticore as “just a little baby”.  
The manticore in the new episode did seem more robust, implying it was an adult in this case.
 
So I guess it’s same deal as “adult dragons = scary, Spike = cute”.

Fluttershy is a very fearful pony; none of her lessons were about getting her to be less afraid. The relevant ones were all about getting her to overcome her fear when it would benefit her to do so (to save her friends in Dragonshy, to give her a place to enjoy singing in Filli Vanilli, etc). She had no reason to step up in this incident, unlike in the second episode, where her friends could have gotten hurt if she just cowered (plus, her seeing the source of the Manticore’s anger might have made it easier for her to step up).

She was worried that the Manicore was going to choke on Trixie.

It wasn’t the manticore, it was the pony being eaten that scared Fluttershy.

Maybe she just wanted to hug AJ, eh? _*wink*^*wink*_*nudge*^*nudge*

That’s because Fluttershy was concerned that the Manticore might actually eat Trixie.

PONE UP, Fluttershy!

@mrdoctorderpy  
yeah sure

@Background Pony #7DAA  
It’s MLP. Everypony has a reset button. Otherwise half of the conflicts would be resolved because the ponies remembered the lessons learned in the previous episodes.

Toonkricticy2k stated that she has a character reset button. I’m not sure which review of his.

Another thing to remember was the Manticore in the second episode of season one was a younger/baby Manticore as far as I recall… (I haven’t watched season one in a while)

@Psyga315  
Continuity, what’s that?

As it was already said. He was going to eat a pony and she knew that. And she had to watch it.

She was scared FOR it. Not scared of it.  
It was in chains and trixie might do something terrible to it.  
When Trixie got eaten she fainted because…well…

@Prof.NightJack  
Nah, she was just scared of Trixie in general.

Wouldn’t be the first time a character changed drastically between seasons.