I think the methodology of the paper is flawed. Why would a time traveller from the future be discussing "Comet ISON" or "Pope Francis"? According to Wikipedia, comet ISON wasn't ever bright enough to spot with the naked eye, and thus left no significant impact on humanity. It's obviously too early to decide if Pope Francis will leave a deep, significant impact, but odds are against it.

For this methodology to really work, you'd need to look for mentions of someone like Hitler in the 1920s (and that's not even evidence of anything as Hitler was slowly ascending to power during the 1920s). But again, why would a time traveller talk about Hitler then? Presumably a time traveller would either be very, very cautious to not be identified, or not, in which case he'd likely get himself revealed through carelessness.

On the other hand, I find it odd that they brush off analyzing the stock market (or any market, really). A cautious time traveller wouldn't buy into the market just before a sudden movement, that would attract way too much attention from insider trade authorities etc. Identify "black swan" events (dot com crash, 2007 financial crash), and look at people who slowly offloaded their assets prior to it. Identify "underdogs" that became huge (eg. Apple in the 90s) and look at people who slowly brought into it during that period.