The video is by Roman on the mailing list I think, and he has been translating/finishing the FG manual and translating wiki pages like on weather, so he is aware of various things to enable/turn-up. 7:15 - 9:20 (direct link) shows flying through clouds close up. The audio is in polish, but shows the new fgtape UI fine without it.
For those testing nightlies, there is also the auto-set feature for the environment sliders to try out. It provides a rough guess at some values - can try changing time of year and watch the sliders change automatically. It's not possible to know things like accumulation of snow and rain, but the values can be used as a starting point by unticking the auto-set button and tweaking manually.
Kind regards