Hi,
As I can see in the data file USDGBP_Jan_2010_to_Jan_2019.csv there are actually GBPUSD rates located there as opposed to USDGBP. Therefore I believe Adj Factor is calculated not correctly in jupyter example. Before multiplying SPY Benchmark * FX rate actual currency rates from the file should be inverted. Let me know if I'm missing something.
Alexander, thanks for pointing that out. Yes, you are right the rates needs to be inverted so that they reflect the USDGBP rates. We will update the data in the course. Thank you.