(Photo: YouTube screenshot)
Holy crap. I freaked out watching this. A science teacher in Russia used a knife and iodine for this intense experiment. It looks like she's cutting her student!
Someone on Reddit explained why it looks like she's getting sliced up:
The color comes from Thiocyanatoiron ions. Skin was rubbed with a cotton ball soaked with a solution of thiocyanate ions, and that knife was covered with a solution [form] of iron(III), which has yellowish color. When solutions have combined, these ions reacted together forming blood red [Fe(SCN)]2+.