[feature request] Stream video directly to FS

There ought to be a solution for taking video and streaming it in as close to real-time as possible to a secure location (keybase's fs). This has some obvious applications with regard to documenting repressive regimes where your phone might be confiscated at any time, but you don't want your video to be easily accessible by authorities via one of the mainstream streaming sites.

Adding a camera interface to the iOS client for this would be relatively easy, but I have no insight into how easy adding the local buffering and real-time uploading would be.

The request concerns the iOS client, camera capture, local buffering, and real-time uploading to Keybase FS, but names no files or tests. Start by locating the iOS camera and FS upload entry points, then establish the buffering, security, and completion requirements before implementation. Done means video reaches the secure FS location with minimal delay and remains usable if the phone is confiscated.

Written by the indexing model from the issue text.