I had the option of this, but decided to choose a local examiner and stick with the traditional viva process, as I was more familiar with this, having seen others and knowing what to expect.
If you do decide to opt for the video conference route, make sure you are fully aware of how everything works and leave nothing to chance, like finding out the firewall has not been opened, etc.
I would do everything possible to make things go to plan on your big day.