You have three choices
1. Use android build of webrtc and any suitable jingle java library to talk directly between users for one to one video or talk to jitsi videobridge for multi user video
2. Use jitsi libjitsi media library with jitsi jingle library to do the same. Look at jitsi android client source code for ideas
3. Use JavaScript to build web app for chrome browser and launch it from your android app.