You could put a helmet on walking down the sidewalk and call it scrambling if that's what it went by.
It goes from hiking to scrambling when you are using your hands to pull on holds.
Let's ask wikipedia what it has to say about the YDS:
Walking with a low chance of injury, hiking boots a good idea.
Simple scrambling, with the possibility of occasional use of the hands. Little potential danger is encountered. Hiking Boots highly recommended.
Scrambling with increased exposure. Handholds are necessary. A rope should be available for learning climbers, or if you just choose to use one that day, but is usually not required. Falls could easily be fatal.
Simple climbing, with exposure. A rope is often used. Natural protection can be easily found. Falls may well be fatal.
Is considered technical roped free (without hanging on the rope, pulling on, or stepping on anchors) climbing; belaying, and other protection hardware is used for safety. Un-roped falls can result in severe injury or death. Class 5 has a range of sub-classes, ranging from 5.0 to 5.15d,, to define progressively more difficult free moves.
To make it even more confusing most people wouldn't consider class 2 scrambling. Class 3 and 4 is what most call scrambling.