Awesome! I found a way to hide the nav bar on Lumia 630.

[nicolasmart]

Ok, so guys, you can try it now. Just follow the steps
Note: It's tested only on windows 10

The steps:
1. Capture a video with a length 5 seconds or more
2. Set up kids corner and add the video
3. Launch kids corner and play the video
4. Tap anywhere to hide the navbar
5. Quick! Lock the screen.
6. Here you go! (until you unlock the screen)

I hope you enjoyed. I just found this bug while watching video with hided navbar because if I'm not in kids corner it's not hided. And mistakenly I pressed the power button. And... Here you are.

 

[jontyfernz]

Ok, so guys, you can try it now. Just follow the steps
Note: It's tested only on windows 10

The steps:
1. Capture a video with a length 5 seconds or more
2. Set up kids corner and add the video
3. Launch kids corner and play the video
4. Tap anywhere to hide the navbar
5. Quick! Lock the screen.
6. Here you go! (until you unlock the screen)

I hope you enjoyed. I just found this bug while watching video with hided navbar because if I'm not in kids corner it's not hided. And mistakenly I pressed the power button. And... Here you are.

Nice discovery but this proves how buggy windows 10 tp is.Gives people another reason to go back to denim especially the casual users