54: How linguists figure out the grammar of a language - Writing a reference grammar book

From a channel Lumen includes in full: Lingthusiasm is a linguistics show by linguists Gretchen McCulloch and Lauren Gawne, with each numbered episode explaining one research topic (grammar, sociolinguistics, writing) with cited sources.

A 41-minute video from Lingthusiasm's catalogue; the title names its topic.

Video by Lingthusiasm, played through YouTube's embedded player.