Her emotional rollercoaster in episode 3 when she thinks she's fallen to her death, manages to recover, makes the Shine appear...and then falls to her death.
In episode 4, her comment "The Piantas are a very dance-iful people".
Her reaction in episode 5 when she spends ages making difficult jumps and falling off to get to a Shine Sprite, only to realise there is an easy shortcut to get there if you have the Rocket Nozzle (which she did have).
In episode 11 she mixes the names "Bowser Jr." and "Baby Bowser" and ends up calling him "Baby Jr."
Her song about one hundred coin missions at the end of episode 13. (She later does other songs at the end of other 100 coin and blue coin missions).
Masae's reaction to the Boos' Off Model design in episode 18.
Her voicecrack while saying "SHINE!" at the end of episode 23 (and her own reaction to it).
In episode 25, she spends ages trying to get a coconut to appear to feed Yoshi while dodging Bullet Bills and collecting coins, making every other fruit spawn on the beach but no coconut. Then one finally appears...and she immediately sprays it into the ocean. And then does it again to the next one that appears.
Masae decides that there must be a 1-up hidden near the start of the special stage in episode 26. She proceeds to die six times trying every possible place before she finally locates it.
In episode 30, her encounter with the glitch that leaves you standing around on the bottom of the supposedly bottomless pit looking up.
In episode 4, she tackles the first special level and, due to the Difficulty Spike, takes many attempts to beat it. However, in the process she gets very good at bouncing on the enemies to get banana coins and extra lives, to the point that when she finally beats it, despite losing many lives she ends up with twice as many as she started with - and 531 banana coins.
Masae's battles with the shop glitch (which freezes the game), especially in episode 14.
At the start of episode 28, Masae plays That Cloud Looks Like with the silhouettes in the background of the first Factory level, including overlaying them with her drawings.
Chuggaaconroy guests in episode 38 and imitates Masae (badly) at the beginning to do her usual intro. He then infuriates her at the end of the episode by hitting the end-of-level barrel and managing to get multiple lots of something other than bananas.
Her squeeing over meeting the Yoshis when she makes it through to Yo'ster Isle.
In Part 10, she has two moments of pre-empting the text. Firstly, when two moles say "If only Mario were here" she says "Speak of the devil...", and that's exactly what the next line in-game is. Then, when fighting Croco and the fight is starting to drag on, she mentions how every time she sees a text box appear on his turn, she hopes it'll be him saying "I give up! You guys are too strong!" and on her next attack he goes down and says something very similar. What makes this so funny is that this is the part where the run becomes truly blind, she hadn't played this part before.
In Part 11 she gets a good Super Jump combo going on Punchinello... only for it to do zero damage.
There's also her reaction to the password to a door being Masae.
She uses Geno Whirl for the first time and gets the timing right for 9999 damage. She can't believe what she sees.
On Episode 23, she complains how expensive it is to pay for the initiation fee and a Beetle Box and is quick to decline* 100 + 50 = 150 coins. She checks her coin count, only to find out she has 999 coins. The camera even zooms in to emphasize that.
On part 33, she gets into the fight with Valentina...and ends up noticing her big boobs. The camera, once again, zooms in to emphasize her brief fixation. Then she sees them jiggle. The endslate even treats us to an endless loop of Peach using her melee attack on Valentina to make them jiggle.
Masae: Her boobs are freakin' gigantic! L-Look at how tiny her waist is! And they're- and- tho- those two big- just boing!
In part 34, she gets obsessed with seeing all the dreams from the Dream Cushion in the inn. She spends hundreds of coins on staying despite having full HP just to see them. Eventually it jump cuts to her saying
Masae: Please please please loop soon so I can stop spending so much money on this... This is kind of stupid actually, I should feel bad. Actually I really do feel bad-WHAT THE FRICK [ dream consisting of a giant fat koopa sleeping on top of Mario. ]
In the same part, a meta example. After massive amounts of comments in previous videos telling Masae where to get the Fertilizer, she ends up finding it on her own by sheer coincidence.
The episode also contains two gameplay-related cases of Late to the Punchline. She finally realises she can sell the Goodie Bag for 555 coins, and finally realises you can scroll down the list of party members on the "equip" screen. She gets... particularly angry at the latter.
Part 39: Masae's reactions to Bowser scaring everyone away. Also, when she prepares herself to fight Croco, only to find that she isn't supposed to fight him.
When fighting Exor in Part 44, he uses Dark Star... and Masae complains about him getting three stars out of the attack when she's never managed more that two with Mallow's Star Rain.
There's also her random digressing when she has Mallow attack one of the eyes. (Mallow currently has cymbols as a weapon)