Pidgin has audio+video? I had no idea, thanks! well, what's left is making it work : I learned that XMPP is the only supported protocol for video+audio. And that I should right-click on a contact to enable the audio+video. Ticked the box at the bottom to create an account on the server. im.apinc.org is the domain name I used.
But I struggled to find such info, even on the pidgin website. What's left is to try it on Windows/Mac, for my contacts.