Steps to repro:
1. Go to Timer view
2. Flip phone to landscape view
3. Press Video button to open video image
4. Flip phone to portrait view
The calibration dialog pops up, and once that is dismissed there are GUI problems, screen being half cut off, etc.
Workaround:
Press the Auto Record button and let the app go back to Timer View naturally, then switch to portrait.
iPhone 5S with iOS 8.1 and latest version of Harry's of this writing.