Took me an hour but I got it! Staring at a solid background on my Nexus 5 on full brightness in a pitch black room did the trick. Horizontal linear oscillation was more noticeable for me than vertical for some reason, which meant holding my phone in landscape mode. The brush pattern is significantly fainter on my laptop than my phone, and I seem to lose the effect every few minutes when using my laptop. I've been able to bring it back by glancing back at my phone in landscape. This is really, really cool by the way.
Nope it's very clear once you know what to look for, as long as you're looking at something highly polarized. I still have this superpower about five hours later.
