Episode 15 of The Witness stays up in the tree houses. Basket works through a long row of orange panels covered in orange and purple suns, then a third color, and watches the solved panels line up into a walkway. After that comes a green panel that mixes suns with small shapes, and a timed run that keeps ending too late. The video ends with both of those still open.
Two of a color
The episode opens on a walkway made of orange panels. "Maybe that's a faster way to get here than the thing we just did." A short corridor through a tree house leads to a small orange panel with two orange suns and two purple ones, and then to bigger 4 by 4 grids of the same kind.
"We need to have two suns of the same color," the commentary says early on, and later, after a solve, "so we can only have two of the same color suns together." Most tries fail on a count: "Too many oranges," "too many purples together." Each solved panel drops flat and the next one stands up past it.
A third color
Around the eight-minute mark green suns join the orange and purple. "Okay, so now we have an extra color that's thrown in." These take a lot of backtracking ("How do I get these oranges separate?") until the last one goes in.
The bridge
With every panel solved, they lie end to end as a walkway through the treetops. "Yes, okay, this goes no way. This doesn't help me at all. What a useless bridge."
Shapes and suns
A green panel nearby has two purple suns and two small orange bars, one three squares wide and one two wide. The commentary works out half of it: the line has to draw those shapes into the grid "with no extra" space, and the suns "need to be together in the same blob." Each attempt fixes one and breaks the other. "Shapes are happy but the dots aren't." After about seven minutes Basket gives up for now: "I'll come back to this."
Racing the clock
Next is a small pink panel on a post, looking across at a wooden box with slats on a tree platform. "We can try this sprinting thing again." A line goes in, Basket runs the walkways and panel bridges toward the box, and it ends with "oh no, I screwed up."
A white panel on a table below gets a few lines. "This one, it made a good sound. If I do something else, oh, that's also a good sound. That was a bad sound." Then it is back to the pink panel for another sprint.
Where it ends
On the third try Basket stays put and watches instead. The box's doorway opens. "Yeah, the door opens, this timer goes." Basket decides "I don't want to do that one" and walks off past a bridge of panels into the red trees. The video ends there, with the green shape panel unsolved and the timed door still out of reach.