If you want to enable people to leave a profile video, you need to cover two separate use-cases: recording a profile video for the first time and re-recording an existing profile video.
While you can roll your own code to do so, you can use our built-in support for that as well. Let's assume that you name every video with the user's profile id. You can then use the following code:
<ziggeo ziggeo-modes="recorder,rerecorder" ziggeo-video="_USERID"></ziggeo>