I got that exact same module in the mail recently and did tests on it.   Firstly I don't see how measuring the current across the input positive and output positive does anything except maybe show the current draw by the circuit or by the meter across the small voltage difference.   Output current should be measured across the output across a resistor shouldn't it?   I can see why he had the output voltage adjusted to only a couple millivolts higher than input.   When I measure the way he did the current jumped all over at first from 200 ma to about 800 ma where it settled.  But when I changed the output voltage up to about 2.5 volts over input volts it was seeing about 4000 ma across the positives.   Here's some numbers for you including some measured across a 15 Ohm 15 watt resistor across the output:
All measurements taken with Fluke 77 and 87 meters:
12.30 V in
12.35 V out
200 to around 800 ma across the two positives
5 mv across the two positives
--------------
12.30 V in
14.78 V out
2.472 V across the two positives
4.072 Amps across the two positives
Current in jumps to 0.63 amps (630 ma) when measuring the current across the two positives
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Now measuring a better way with a 15 Ohm resistor across the output:
V drops to 10.57 in
current is 960 ma in
or 10.1472 watts IN
V output is 11.41
current out is 780 ma
or 8.998 watts OUT
efficiency = 87.7%


I saw no reason to short across the positives when measuring with a resistor across the output since the negatives are connected internally and if you connect the positives together you are essentially (totally) bypassing the voltage converter module.   


No OU here. 


My module and resistor shown - same exact module as in the video: