I see the Robbo pilot landed on the wrong type of grass.
This is something all pilots train for in reputable schools, I would suggest. Long grass grown from inferior seeds is a major risk to helicopters - everyone learns this.
Teaching how to identify various strains:
tufts, weeds, course blade formations, direction of growth - it's all there in the HOGE/HIGE section (hovering inside grass effect etc). Honestly, some pilots.