from Hacker News

This may not be new for many iOS developers who tried Yosemite beta but new for a new Yosemite user.

I was using Reflector all the time to share my iOS device screen with my MacBook for demos. With OS X Yosemite, QuickTime has a fantastic feature to record from iOS device connected to your mac (over lighting cable).

- Connect your iPhone/iPad runs iOS 8. - Fire up QuickTime player and new movie recording - Choose iOS device from the drop down menu next to record button. - Even the microphone and camera can be used.

Looks like this is more of a developer feature to prepare app preview videos for AppStore.