weather modification in that form is nothing new, hidden or sinister. That's as if you said: this car salesman just admitted that he is selling cars... I personally don't believe in chemtrails. Like many other conspiracy theories (and by many i definitely mean many and not all) "evidence" just isn't there, and documentaries on this subject (at least the ones with most views on youtube which i watched) are just ridiculous. People will measure higher level of something in earth and claim it must be from the plane which passed earlier (at 10km altitute).
Having said that, I don't think any of these two managed to prove or debunk anything. That Joe Rogan sure has a huge ego though.