Good Videos!
I've also seen a similar setup where a manometer is used...
A similar tube device is threaded into the #1 sparkplug hole, but this tube travels up, then down, then up again. In the "down then up again" section some oil is captured, & using just air pressure from the cylinder you can watch this oil travel up as the cylinder is advanced towards TDC.
The down side of this setup is that any small air leak (in the device, or past valve seats) will cause inaccurate results.
I like John's method.
Worth noting is his mention that you'll need to get most of the oil out of the cylinder prior to starting the car. IF you don't you'll be trying to compress this oil and you could damage the engine. I'd use a suction device to get most of it out, then maybe blow out the remainder with compressed air.
(I've had more than one occasion off-roading where I've attempted to cross a stream that was a bit deeper than expected and LITERALLY Flooded the engine (with water). After winching my Jeep out I would remove all the spark plugs, put the trans in gear and push the car a few feet to force most of the water out of the cylinders. OTHERWISE you'd be trying to compress this water and you could damage the engine.)
"Cheers!"
-Bear-