At Mysterious Universe, Paul Seaburn writes:
In what can be considered an unusual convergence of conspiracy theories, a man who runs a Bigfoot videos YouTube channel was chasing chemtrails when he claimed to have recorded a UFO chasing them as well. If you’re playing Conspiracy Scrabble, ‘Chemtrail’, ‘Bigfoot’ and ‘UFO’ is a triple-word score.
According to his commentary during the video, Marc Abell –the CEO of Colorado Bigfoot, a provider of Bigfoot videos – was recording a plane making a contrail over a snow-covered terrain in Vail, Colorado, and believed the color and shape changes in the contrail were signs that the plane was actually spraying something rather than just trailing the usual water vapor and jet exhaust.
That's when Abell spotted the UFO.