Quote from Port1385:
Notice in the video how he uses the 13 and 43 week moving averages as a "sell signal".
In Nov 2000, these two averages crossed and then began a huge downturn in the spy. Sometime in 2002-2003 the averages crossed again. Since that time, there have only been a few brief crosses during the upturn.
The recent cross in January makes me wonder if we might have another 2 year downtrend. The indicator that he uses, if backtested, is reliable enough.