I wouldn't put too much stock in youtube videos - Mythbusters have put many of these types of videos to the test and found them fake.
I didn't review all the video's turned up in the search list, so there may have been some fakes within the list.
That said, a focused beam of sunlight can start a fire when suitable tinder is present. Just as heat generated by friction and anything that produces a spark can start one, too. In the hands of someone who has mastered the technique, an
empty BIC lighter can be used to start a fire.
Please don't fall into an unexpected trap. For example, just because there are some fake preachers doesn't mean that every man preaching the gospel of our Lord is fake.
Within arms length of where I'm typing these words there are:
Magnifying glass
Fresnel lens
Bic lighter
Magnesium Bar & hacksaw blade scraper
Ferro Rod & Striker
Couple of arrow heads (flint) & carbon steel (pocket knife)
Flashlight with batteries
Mylar inside a bag of chips
Shoe strings (for a bow drill)
and a couple of books of matches
Plus plenty of tinder/fuel, including the expected (paper) and unexpected (gel hand sanitizer).
I have no doubt that a "shiny" dog bowl could have started that fire.
Makes me glad I have a brick house!!
