I do not want my users to see the permission window (for granting access to the camera/microphone) each time they launch my app. What should I do?

If you use an HTTPS URL for your application instead of HTTP, the Chrome browser will remember your user's permission settings and does not prompt them every time (as long as they are accessing through a non-incognito mode).

This only applies to Google Chrome. At this time, there's no workaround for Firefox or Internet Explorer.