I have now had more experience with this since the video went up. I find that it is still true. The part I want to emphasize is that the topic is EVERYTHING! When I do a non-topic livestream (such as "Playing COD Ghosts with Friends") the video does about as well as any other video, perhaps 10% better. When I have a hot topic selected, the video easily gets 5-10x more views. My most popular livestream now has 80,000 views, and I have less than 5k subs.
I should also note that you can't expect to put out these videos all the time. Depending on your field, hot topics will come up only time to time. In gaming for instance, key events that can be capitalized on are: new game releases, new console releases, game patch/update releases, console update releases, game info/trailer releases. Times like January, there are no hot new releases, and barely any other updates. This leads to fewer big-hitting videos. Strike while the iron is hot and take advantage of the growth, but also realize it isn't something you can replicate for every video.