Any type of connectivity over Bluetooth will be subject to latency (delay). A standard Bluetooth connection has around ~200ms delay, which often causes significant lip-sync issues when watching videos/movies. Qualcomm's aptX used by your Nuraphone is a Low Latency codec, that should dramatically improve your experience.
If you're watching online videos with your Nuraphone and are experiencing a delay between video and audio, can you please:
Use the full screen mode on YouTube or your chosen video player.
Restart your mobile device or computer.
Clear the app cache you’re using.
Connect to your Nuraphone via a cable for a low latency connection.