1. Firmware version: .78
2. App to play video (video title where you experience this):
YouTube:
https://youtu.be/G_tLIX4aRj0 (1:21) (720p)
YouTube:
https://youtu.be/LZotNSWF0-4 (0:43) (720p)
3. Brightness setting: 20%-60%
4. Screenshot:
Interesting info: there seems to be no black crush if i lower the brightness anywhere from 15% to 0%. If i do that, the black crush disappears and the red tint takes place. The lower the brightness, the stronger the red (happens only on YouTube). Also, less black crush for me above 70% brightness. The higher, the better.
Conclusion: black crush occurs in YouTube at 16%-69% brightness. Around 45% brightness is where the strongest black crush happens.
Disclaimer: This info is based only on those two videos. I might be wrong and there are other videos that still exhibit black crush regardless of brightness.