I’m interested in this too. There doesn’t seem to be any way to control the camera during a mission. As far as I can tell there are no blocks to control the camera like start/stop video or take photo. This would be an amazing addition and would be a feature I’d pay for.
The Tello SDK does provide a video feed. It's up to the creators of apps to use it or not.
On these forums someone created a wrapper library for the Tello using python which provides a video feed. If you know python it should be pretty simple to record that stream to disk while doing some coded mission.
Unfortunately that's not possible with the droneblocks app (yet).