The official YouTube App version 1.4 for iOS updated and brings Video suggestion.

Available today, like video on Instagram, this new version for iOS brings video suggestions; closed captions to live streams and some
fixes for the overall performance.

Overall we have :

• Video suggestion overlays for what to watch next
• Closed captions for live streams 
• Stability improvements, including fix for application crashes

YouTube for iOS is available for free as a universal app (iPhone/iPad/iPod Touch).