How much more controlled do you want? I didn't see his first video but, based on his comments from feedback by viewers, he modified his tests to be more controlled and objective. I have a lot of experience with removing stubborn fasteners from rusty old Volkswagens and have acquired many tips from my own experience and from others.
One technique I've heard of is to melt a candle or even a crayon on the threads of the stuck fastener. Some guys believe any fastener will be properly treated if sprayed with gobs and gobs of penetrant. Unfortunately, that's not the case. A lot of people advocate the 50/50 mix of acetone with ATF, but I am dubious the mixture works since the two substances tend to separate almost immediately after they are mixed. Straight ATF should be enough to accomplish the task. I sometimes go the extra step of heating the fastener with a propane torch and then applying penetrant since the liquid will immediately evaporate and cool the part. This tends to help draw the liquid into the threads.
I figured it would be a helpful video, especially since the one penetrant didn't appear to seep into the rusted threads. I thought his effort of mixing all the penetrants and applying the combination to the rusted part was ridiculous.
2006 Mazda 3 2.3L Hatchback 5-speed Automatic - 180K miles
I never purchase Harbor Freight tools.