http://StopSprayingUs-SF.com - Yet another bad day, but an illuminating one. At the 0:01 mark, you see a plane leaving a very short-lived, quickly fading trail, but soon after a new trail forms along it's flight path. This adds credence to the position that planes not leaving visible trails can actually be spraying hydrophilic compounds which attract moisture from the humidity of the air and form artificial cirrus after the sprayers leave the scene of the crime.
This explains diffused trails that suddenly appear out clear blue sky, for example the one at 0:22 and onwards. At 0:34 you can see a short trail with very clear start and stop points in the lower left hand side of the screen. From this poing onwards, it's an ugly mess with sickly looking wispy crud filing the sky until sunset.
Just nasty.