Hi Jodi! The bulk fermentation stage begins right when mixing ends and lasts until the dough is divided and preshaped. Many bakers will incorporate some stretches and folds throughout the bulk fermentation stage to help them assess how the dough is progressing. Most bulk ferments are done at room temperature, however, it certainly can be done in the fridge. Just expect a much longer rise time since the rate of fermentation will decrease with the lower temperatures. As for videos, we have quite a few both on our YouTube Channel and our website. Here are the links to access those pages: 

YouTube Channel

Videos on kingarthurbaking.com

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