JumpInChat uses a technology called WebRTC for video streams, which is a way to transfer data to and from a browser. WebRTC is supported on the latest versions most major browsers except Internet Explorer. In order to view and broadcast you will need either Chrome (or other Blink-based browsers) or Firefox. It should also work on later versions of Android (e.g. Chrome Mobile and Samsung Internet).
Safari and iOS currently do not support video, all broadcasts will be received as audio-only. Safari developer preview currently supports the VP8 video codec required to send and receive broadcasts. This is, however, only available for desktop. Though it indicates that the future will allow for Safari support.
In order to broadcast, your browser must have permission to access your audio and video media sources. Your browser should ask for permissions for your webcam and microphone when you select them, but you can also define them yourself from the site settings dropdown in your browser.
Screen sharing is supported for desktop browsers only currently (Chrome and Firefox). Firefox supports it out-of-the-box. Chrome, however, requires an extension due to increased restrictions on permissions. You can get the Chrome extension here. It is provided by Meetecho who develop the media server JumpInChat uses for managing it's streams.