Video transcript
Column one has a clue of five and exactly five cells, so the whole column is filled. Both left corners are now guaranteed, including the top-left anchor used next.
Row one needs a run of four and its leftmost cell is already filled. Because that cell touches the edge, the run must extend through cells two, three, and four. Cell five is empty so the completed run cannot grow to five.
Row two has a clue of one, and column one already supplied that single filled cell. The run is complete, so every other cell in row two is empty.
We now know all five cells in column one, row one, and row two. After removing their overlaps, that is thirteen distinct cells out of twenty-five—more than half the grid without a guess.
The reusable chain is: solve full lines first, use edge fills as anchors, close completed runs with empty marks, and scan the crossing clues for the next guaranteed move.