[robotrout]

This is exactly the same premise as TrueCrypt. Nobody can know if there's anything on a TrueCrypt volume or not.

They address the coercion (either by law enforcement or guy with a gun), by allowing you to make hidden volumes inside the main volume. You open the main volume, filled with data you don't care about, and they never know that a hidden volume resides deeper.

I see no reason that this same technique wouldn't work here. You record some boring video on the main volume, and record your main video on a hidden volume.

[thaumaturgy]

IIRC, some minor vulnerabilities to TrueCrypt's DFS were found.

Ah, found one link: http://www.schneier.com/paper-truecrypt-dfs.pdf