two preliminary steps:
- be sure you can Live Cast on Youtube from your PC
- be sure that you can view your drone POV
The third step is to match the two pieces together. Two options:
- Drone->PC PC->Youtube (viable & recommended)
Assuming you're opting for option A), you need to download the YouTube Live Encoder for your platform (Win/MAC). https://support.google.com/youtube/answer/2907883
Unfortunately this depends on Youtube Live policies and may vary (again) in the near future.