For live streams you will need to publish and send the stream to Wowza from an encoder such as the options I listed in my last post. Or, Wowza can pull a stream from an IP camera. Also included in my last post is a guide for this. Once the stream is published to Wowza, it can be recorded and saved to mp4.
Wowza does not support pulling a stream from an HTTP source or from a built in web cam without an encoder to push the stream to Wowza. You can use GoCoder to send a live stream from a smart phone to Wowza. I linked to that guide as well. Again, once the stream is published to Wowza, it can be recorded to mp4.
If you want to have the user record a presentation, review it and once approved stream the mp4 you will need to add the file to the /content folder of the Wowza install and use a VOD application to stream the file. The recording process in this case would be done locally and then uploaded to the Wowza content folder.
Lastly, Wowza can play the recorded file as a live stream, but that would be a different workflow and I am not sure exactly what you are trying to do or if that is what you want to do.