Brittleware
What you state regarding the recording of take offs/ landings I'm sure has been brought up before. If anyone has seen the B2 footage from Guam, you'll notice that this was taken from a "Security Camera" at the base, that was watching the departure of the B2's. Although it doesn't answer all the questions, it can help. In the B2 instance, you can see something detach from the aircraft and its pitch for rotation is way too steep, which results in a stall and the left wing clipping the ground.
Like you say, video footage would have provided vital evidence.
Maybe someone more in the "know" will be able to explain why it hasn't been put into affect, but I know it has been suggested countless times before.
EDIT: Just see that someone has posted that such cameras were in use. I'm sure they will show some vital information. Are they now a requirement or "Advised" to have them?