I've been observing the sky for 50-60 years, where contrails were not a usual thing in the mid-1950s. Now they can be seen all the time. There is a wide range of contrails and nothing distinctive that would merit being called a chemtrail. The proof can be conclusive: documentation of spraying equipment in a commercial airliner. But it has to be proven that it is spraying equipment and not some ordinary purge vent. You won't find it. The plumbing needed for that sort of equipment would be completely noticeable during factory assembly, which happens in a very big place with lots of people involved. No such equipment on board.

You just have some idee fixe of what contrails are and aren't...and you are wrong. The idea that they are quickly transient is very mistaken. They are only a form of cloud, and clouds can vanish or linger.

A book can be taken seriously, because the lack of supporting evidence citation would be a glaring omission. It is possible to verify the information independently. Videos are meant for the undiscerning eye and grease by without any means of verification, stitched together with lots of unsubstantiated allegation. Once it is cooked up, there is no independent means of verification, as there are no objective details to verify. You don't win a legal case with "Check out this video, Judge."

Another reason I don't take you seriously is that you belabor "chemtrails" from utterly innocuous contrails---yet completely bypass the authentic huge chemical plumes resulting from space launches involving large solid-propellant boosters (hydrochloric acid and aluminum oxide dust). Somehow, that is beneath your notice, and everyone admits to what those plumes amount to. Yet, the weather washes it out of the sky and the southern Florida air is fresh again. You get excited where they aren't, and don't give a shit where they unmistakably are. You just aren't serious or consistent in your concerns.