-다가 marks the activity you were in the middle of, and what follows is almost always 알게 되다 rather than plain 알다, because the knowledge arrived rather than being sought: 저도 찾아보다가 알게 됐는데 'I found this out while looking something up', PD 님이랑 얘기하다가 알게 됐는데. It is the standard way an explainer video introduces a fact it stumbled on.