Hey, my coworkers and I built https://OpenTokRTC.com to test OpenTok (also a webrtc API) video streams. We've tested it with 15 people a year ago and it worked great. I would imagine that they have improved even more at this point in terms of scalability and quality. You can also test the android/ios companion apps, they all interoperate pretty nicely. As an added bonus, they also support real time video recording and playback, which is really nice.