If your users' webcam videos get out of sync during the recording, this is likely caused by the fact that at the time of recording:
- the computer is either occupied with concurrent tasks that use (too) many of its resources (notably: CPU cycles), such that it cannot fully "keep up" with the recording;
- or the user has pushed the browser window/tab with the Clipchamp widget into the background, where the browser (and on macOS: the OS itself through the "AppNap" feature) throttles the resources;
The best option to avoid this is to advise your users to shut down/pause any concurrent jobs and to keep the browser window in the foreground.
There is also a setting in macOS that users can toggle, which prevents macOS' auto-throttling of background windows (see e.g. http://osxdaily.com/2013/10/29/disable-app-nap-per-application-mac-os-x/).