Its simple...he saw price going higher...getting above a resistance area and then pullback below that same resistance area to then continue back lower...below prior support area.
Not sure why he called it "dramatic" unless he's referring to the increasing tick volume and volatility although my data shows such is normal in price actions as such when that happens. Simply, it happens often...its normal to see.
In contrast, something dramatic to me is something I don't normally see but the word I would then use is "unusual". Anyways, there was also news out of Europe in that price area he's talking about although I don't know if the news was the sole reason or part of other reasons.