Yunari TV is a youtube channel set up by idol sisters Yuna of AOA and Seoyul of Berry Good.
Together (Yuna + Yuri) make Yunari!
The girls are both main/lead vocals so the channel consists of various song covers as well as vlogs.
Only four members are in the AOA vlogs as Hyejeong was filming a drama.
sources: Yunari TV (2, 3, 4, 5, 6, 7)