I used the same technique for checking the bushes in my Discovery 3 (the vehicle recorded on that video). The rear bushes on the lower arms are hydrobushes and fail with alarming regularly
The Freelander bushes last much longer.
I've used an old Galaxy S 3 phone taped to the chassis before now with good results. Luckily the phone didn't fall off!
I have a USB endoscope too which I use for the same thing, also taped into place underneath.