I'd vote for any of a number of species of mosquito, since various mosquitoes transmit such diseases as malaria, yellow fever, encephalitis, chikungunya, etc., affecting many times more people (and animals, for that matter) than the biting or stinging bugs you might otherwise think of.
Tucker

Fleas would have been a candidate for most deadly insect back in ancient times (plague), mosquitoes would win today.

I didn't watch the video past the intro; it's for young children. I doubt that it covered insects at all.

No question that mosquitoes are the most deadly insect.

I have a cousin who moved to Costa Rica with her boyfriend years ago, and she was bitten by the wrong mosquito and got Dengue Fever. Its supposedly really rough and you are deathly ill for many days. Then you will probably get better with treatment, but she said if you get bitten by another Dengue Fever mosquito you may die the next time, after a very long and painful sickness....

We moved to a new home in rural Pa after my Dad was transferred by a large textile fiber and chemical company. He worked in the city, but had no desire to live there, so he moved us to a fairly large home on about 1-1/4 acres. Problem was, the back 2/3 of the property was overgrown because it hadnt been mowed for at least a full season, so our family rented a bar sickle mower and my Dad ran it while we picked up the cut debris and stacked it. In the process, my Mom picked up a tick. Not long later she became very sick. Turns out she had Rocky Mountain Spotted Fever. That was pretty rough...

In my country, it'd be the black widow spider, or the brown recluse.

Dan, spiders aren't insects. But even at that, disease carrying mosquitoes can be deadly....for millions worldwide. The spiders you've mentioned are venomous but very rarely deadly.

My garage is home to numerous BW spiders and they couldn't be less interested in us.