Why is join in this sentence in the past tense?

Native speaker’s answer
Rebecca
There are two possibilities here! Either the clip was filmed earlier in the day, so he uses "joined" in the past tense. Or, they're talking about his actual physical movement from London to their current location. That movement, or "joining," would be a past action. Ex: Here's a clip from earlier in the day, where Barbara joined us to talk about the ocean. Ex: I joined my family here in London, after staying in Wales for a couple of weeks. Ex: Now, joining us live from London, is Sarah.