Mean Reversion vs. Momentum Strategies

This is an interesting interview. About half way through he makes a deep point that if you use an oscillator type indicator and sell it when it is overbought and buy when it is oversold that is a mean reversion strategy. If you do the opposite - buying when overbought and selling when oversold then it is a momentum strategy. And those are really the only two options for directional trading using such indicators. Well, he also says that 95% of assets follow a random walk and can't be predicted. My system basically tells me when to switch between momentum and mean reversion. For me there isn't really something that is not predictable though when volatility is low predictability goes down.