cool.. but not all use magnetic pulses (seen vintage counterexamples)...
w/o reading the article (~5am here.. I'll do that after I got some sleep

)
I wonder how he'd adjust for the "current readout" since counting pulses [and dealing with overflowing counters]
might not give absulute values at all, at least not the correct ones (even if some precompiled startvalue is set)
Anyways..
to just take the ticks, indeed no camera is needed, an optical mouse sensor does the trick as nicely even on non magnetic wheels

(I wonder if you could actually even read digits with a mouse sensor)
Anyways, a cheap webcam is not much more expensive than an optical mouse...
Soo let's see what size that fortune would have to be to make such thing work:
Arduino nano (10 bucks) [chinese clone pack of five for 5 bucks on ebay]
webcam [call it 20]
wifimodule [WITH BT! another 15]
5v wallwart [those usb phone chargers... 5 bucks?]
some wires, solder and time... [i'll call it free]
50 bucks .. I'd say, likely cheaper if you go for chinesium clones of known modules.
Add when needed:
card reader (5'ish)
motor controller (20)
motor power supply (10)
gearing mounting stuff (20)
(another 55-60 for remote shutof valve and constant data logging)
most people these days happen to have some sort of sub par webcam in some drawer that's certainly good enough for such task,
most kept an old charger for an old phone they're no longer using (or even having),
some people (me for example) have unused nanos laying around since they got a bag on ebay for cheap (and needed just one...)
I'd say I'd need to spend 15 on the wifi/bluetooth module, everything else I should have *shrugs*
Or to put it in different words: it's not as expensive to play around with such non invasive ideas as one might think..
I bet some people basically can do such thing for FREE (having all the parts and time required at hand)
'sid