While it's not really clear if the TMNT can understand other non mutant turtles or reptiles, but what if they could, and watching Nature Shows had a different reaction from them, just because they understand the critters on screen?
Whether it's just they understand the tone, or if they hear it like the turtle on screen complaining about everything around it, is up to personal interpretation.
I heard/read this concept before, but the idea that April/Casey walks up to them watching turtle videos, mentions it looks interesting, then one of them says like:
"The Softshell is telling the Slider on it's back about how another Softshell ate her mate."
"Apparently a turtle on the other side of the pond has been pooping on the good plants on purpose, and now everyone is mad,"
"While reptiles aren't usually monogamous these two are talking about how one of thems mate was coupling with their best friend."
Or on the other end (just a understand tone):
["The Softshell is annoyed at that Slider for taking their food, and it threatening to eat it."
"Is it actually saying that?" April/Casey
"No, but the sounds you probably can't hear imply this to us."]
Okay, but can we talk about that whole sequence where the bros were fighting those guys to find out more information on Superfly and how great the editing and choreography was the whole time?
Just each time they entered one of the room, a different turtle was in the lead for each location and got a chance to shine with their style of fighting being the main focus, and that one shot where they all run in sync while tackling the goons.
Let's not forget this one shot right here:
Whoever did the storyboard for this scene, well fucking done cause this was honestly my favorite part of the movie.
I spent more time that I should have on this silly comic strip so y'all better appreciate it lmao... Anyways, my headcanon for the next movie is that the boys will freak out when they meet Shredder for the first time, probably catching them off guard while they're just vibing and doing random teenage stuff.