Q: Video/Audio

You should do this:

1. Make sure that the sound is on and volume is up with the buttons on the left edge of the iPhone.

2. Reset the iPhone by pressing and holding the sleep/wake and home buttons and releasing them, when the Apple logo appears on the display. Then test again

3. Backup your data and restore as new as described in http://support.apple.com/kb/HT4137

Then test again.

4. If the issue is still there contact Apple, as you will need repair. Before you call find out about your warranty and support status from https://selfsolve.apple.com/agreementWarrantyDynamic.do

There is nothing we can do here, if a repair is needed, and that is what you have clarified now.

Best of luck!

If you just want to record audio, try Recorder Plus:

https://itunes.apple.com/us/app/recorder-plus-ii/id502271511

If you want to record both audio and video in SYNC, try:

Nolan LiveMIC Bluetooth Remote Microphone - http://amzn.to/1VfAbqI

Captures app - https://itunes.apple.com/us/app/captures/id898573489

[I do use these combo and they work awesome!!]

For a lag-free recording, use:

Nolan LiveMICRX Bluetooth Wireless Remote Microphone Transmitter and Voice Receiver Set

http://amzn.to/1Wma7un

HTH

Use this solution for crisp and broadcast quality recording:

Rode SmartLav+ - http://amzn.to/296LbrH

Rode SC6 Breakout box - http://amzn.to/292JOrD

Rode SC1 TRRS Extension Cable - http://amzn.to/29nvCdg

Works great for me!

HTH