I'd really love a video call tool the quality of Mumble; a few basic features, reasonable call quality, low-latency and fast reconnects. Skype and Hangouts never came close to that for me.
Realtime multi-directional video over the Internet is pretty high on the pyramid of software complexity. There are a lot of corner-case problems that can only be solved by rolling up one's sleeves and building one-off solutions for a variety of hardware, OS, and browser quirks.
To my knowledge, no open source project has attracted enough critical mass to have the army of supporters that can get in and solve those problems. It's boring, glory-free grunge work, so good luck finding people you aren't paying to get it done.