If you already have an URL you might try this from the appstore: https://appstore.home.mendix.com/link/app/2578/Flock-of-Birds/JW-Player
Otherwise it is more a stackoverflow question: https://stackoverflow.com/questions/24675596/show-camera-stream-in-canvas-video-using-phonegap
HTML5 might also be an option: https://www.kirupa.com/html5/accessing_your_webcam_in_html5.htm
The streaming is done by the RaspberryCam, so your Mendix app only has to show the streamed footage. The widget “Audio Video Playback” form the appstore does the trick. When you have downloaded this to you Mendix App, add a widget ‘Audio Video Playback Embed’ and add the URL. And you’re set to show the Raspberrycam.
See https://mydemoversion8-sandbox.mxapps.io/p/webcam for a (partial) demo.