I am merely talking about using a different setting on your test oven than "dehydrate" such as "bake" to avoid excessive air circulation from the fan to mimic real world conditions.
It is a fan oven, the fan will be used for "bake" as well as dehydrate, but "bake" has a few issues, such as including an unwanted pre-heat cycle, which goes to the wrong temperature, an automatic conversion of oven temperature to fan oven temperature, so that you can follow your recipes without needing to convert yourself, so it unhelpfully doesn't operate at the temperature you set! And I wouldn't be surprised if it also unhelpfully grills the dashcam a little as part of the bake process.
Dehydrate is much simpler, allows lower temperature settings, gives the correct temperature, and prevents accidentally using plastic melting temperatures.
If you want to remove the air circulation, you would need to put the cameras inside a box, which would have been inconvenient. and taken longer to do the test since the inside of the box would warm up much slower. A sealed box would also enable control of humidity, which will have some effect on cooling performance, but I don't think it matters to the results and is unlikely to change the ordering of the dashcams, and in any case, some dashcams get used in hot humid places, some get used in hot dry places!
This test was an interesting experiment, but I'm not sure what the results mean. I certainly wouldn't score the 70mai highly, since it shut down at way past useable lithium battery temperature, and it has a battery, not a supercap. I think I am probably happier with the lowest shutdown temperature of that group, to get long life, but obviously some people really want 24/7 parking mode, in hot regions, and are prepared to replace their dashcams frequently. So we don't need exact results from this testing, just an idea of which cameras will operate in relatively hot conditions, which shut down at more reasonable temperatures, and which fail to shut down, so are likely to die quickly.
To be a really useful test, we want to know how long the cameras can survive at those temperatures, but nobody is going to do that test, except for some of the manufacturers testing their own products, and by the time someone had completed that test, there would be another generation of dashcams to buy, which would have different results.
Nice video, but the results shouldn't be taken too seriously, and certainly not as "this dashcam is best because it ended up at the top of the list"!