Most of this video is about method rather than measurement: where a stop belongs, how to measure the distance to it, and how to size a position from that distance. Those are arithmetic and process, and they carry no factual claim to check.
One part of it does make a claim about how markets behave, and it is checked here.
The video says that stops placed below obvious equal lows, above obvious equal highs, just beyond a clean support or resistance line, or right at a round number tend to sit where other traders’ stops sit, and that those areas contain liquidity price can reach into.
This is documented. Osler’s study of individual currency stop loss and take profit orders found clustering in both, and used that clustering to explain two behaviours traders already describe:
“This paper documents clustering in currency stop-loss and take-profit orders, and uses that clustering to provide an explanation for two familiar predictions from technical analysis: (1) trends tend to reverse course at predictable support and resistance levels, and (2) trends tend to be unusually rapid after rates cross such levels.”
Osler, Carol L. (2003). “Currency Orders and Exchange Rate Dynamics: An Explanation for the Predictive Success of Technical Analysis.” Journal of Finance 58(5), pp. 1791–1819. https://onlinelibrary.wiley.com/doi/abs/10.1111/1540-6261.00588
The working paper version is open: Federal Reserve Bank of New York Staff Report No. 125. https://www.newyorkfed.org/medialibrary/media/research/staff_reports/sr125.pdf
The video says price can push into a stop cluster, trigger the stops, and then reverse, and that this is why a stop sitting in the most obvious pocket is exposed.
The reversal half is the first of the two behaviours in the passage above. The speed half is the second, and has its own study:
“In this paper, I provide evidence that currency stop-loss orders contribute to rapid, self-reinforcing price movements, or ‘price cascades.’ Stop-loss orders, which instruct a dealer to buy (sell) a certain amount of currency at the market rate once the rate has risen (fallen) to a prespecified level, generate positive-feedback trading.”
Osler, Carol L. (2005). “Stop-loss orders and price cascades in currency markets.” Journal of International Money and Finance 24(2), pp. 219–241. https://www.sciencedirect.com/science/article/abs/pii/S0261560604001147
The whole argument rests on there being a level worth placing a stop against. Support and resistance levels supplied by working foreign exchange firms were tested directly:
“Support and resistance levels — points at which an exchange rate trend may be interrupted and reversed — are widely used for short-term exchange rate forecasting. Nevertheless, the levels’ ability to predict intraday trend interruptions has never been rigorously evaluated. This article undertakes such an analysis, using support and resistance levels provided to customers by six firms active in the foreign exchange market. The author offers strong evidence that the levels help to predict intraday trend interruptions. However, the levels’ predictive power is found to vary across the exchange rates and firms examined.”
The caveat in that last sentence is real and is not dropped: the levels helped, and how much they helped varied by rate and by firm.
Osler, Carol L. (2000). “Support for resistance: technical analysis and intraday exchange rates.” Economic Policy Review, Federal Reserve Bank of New York, 6(2), July, pp. 53–68. https://www.newyorkfed.org/research/epr/00v06n2/0007osle.html