So as others have said, a lot of the information in this video is not true or comes from questionable sources. We know very little of their family as they are very private. As such I've compiled a bit of information we know is absolutely true because it came from the members themselves.
Namjoon has a younger sister and I couldn't find any reputable sources of what his parents do. He was in the top 1% of the country in school, and his parents did want him to have a stable job, but he snuck off to do underground rap.
Jin is indeed the youngest in his family and has an older brother. This section was probably the most incorrect. He's talked about how his father's company has influence in Germany as the video has said, but he's denied on weverse that that is his mother. He's also said he had a normal middle-class family, not a rich one. He has opened a restaurant in Korea with his brother.
Yoongi has an older brother and we don't really know what his parents do. The thing about his grandmother is a rumor only. He's talked on vlive about how his family came from a high-ranking Min Clan, but that doesn't necessarily mean it's connected.
Hobi has an older sister Jung Jiwoo who is an influencer. They look a lot alike and he and some of the members were present at her wedding. Everything that was said in the video about Hobi was true and a lot of the information is from his song MAMA.
Jimin has a younger brother and from what we know, his father is a very kind and loving father. He's also very supportive, but we don't know much more than that.
Taehyung is the eldest in his family with a younger brother and sister. Everything in the video about him is true, except I couldn't find a reputable source for his father being an artist or Taehyung talking about it.
Jungkook has an older brother who is an artist and draws and animates. Most of what the video has said is true.
Anyways, it was great to see this reaction, and I'm so excited for merch. <3