In "Bigfoot is Gay", after Bigfoot kills Dane Shawson and saves Ian and Anthony, the two immediately throw the net over him. At first they're excited that they're gonna be rich and famous, but then they look over, see Bigfoot crying, and look at the picture of Bigfoot and his children and immediately decide to set him free. Sure, they threw him off a cliff immediately afterward thinking he could fly, but it was still a nice scene.
"Merry Christmas, little guy."
In "My Bobblehead Is Evil", Anthony refuses to kill Ian when his bobblehead tells him to, and stops him when he tries to kill them himself by killing himself so the bobblehead dies with him. The moment is lessened somewhat at the end when it's revealed that Ian had been Obfuscating Stupidity and working with his own bobblehead to kill both of them.
Granted, pretty much the entirety of "Life Better-ers" is about Ian and Anthony trying and failing to help other peopledue to missing the point, but the idea of them going out of their way to help others is still heartwarming. Especially when, even if they fail at fixing the obvious problem (such as seeing a kid with a broken and bleeding leg), they still help with something (such as fixing said kid's bike wheel).
In "MY BOBBLEHEAD IS EVIL!", Anthony adamantly refuses to kill Ian.
"No one! Is going! To kill my friend!!!"
And then it's entirely ruined by the ending. The scene was still heartwarming though.
The ending of "We're Stuck Together". Although they fought and bickered like an old married couple, they both admitted that in the end, they were happy they got to spend more time together.
Only to be ruined when it turns out Ian stuck them together with super glue to prank Anthony and forgot about it. Then they proceed to fight again.
In Anthony's Draw My Thing, Anthony reveals how he and Ian became best friends, saying he was glad that they had met. He also explains how he got over being one of the shiest kids in his school, and how the years he's spent on Youtube have been the best of his life.
In a very twisted way, the end of "Smosh vs Zombies" is this. Ian and Anthony realize they could be best friends for ever if they become zombies, so they infect themselves willingly. The video ends to them killing survivors together to another friendship song.