Here one my favorite archived videos. It is from one of my Ale fermentations back circa 2010 in Puerto Rico. Was a stout fermenting with our house yeast. I had cropped fresh yeast from each fermentation over three years - must have been Generation 80+. What I like about this video is that you can really see how vigorous this fermentation was - I call it a "rolling fermentation" kind of like a "rolling boil" in the kitchen. In German, it's also called a "Kochende Gaerung". Cheers!