Build video capture Unity script with ability to write on screen, must capture audio.

We require a Unity script that allows recording (like a normal camera app) but also must allow the user to draw on the screen. The user should click a start button (once clicked video recording starts, and audio is recorded) - the user will see the video on the screen AND the user can draw on the screen (or any other input method). The button that said start will now say stop (because user is recording). After completion the video should be stored under the application's files. Another freelancer tried to do this and failed (TopTower22), you are welcome to record audio into a separate file if that is only way you can make this work - as long as you can have them able to be merged on a server but you will need to upload to a web service if that design is taken. Deliverable must work on several Android phones and iPhone. Must include source. All code must be original work (ie no third party tools used unless approved by us, we need to avoid potential license problems). All work and code will be copyright by us.