These videos of retardant and water drops by single engine air tankers were published by the Colorado Division of Fire Prevention and Control.
Below is the description for the above video provided by the CDFPC, and following that is the description for the second.
“Bitter Creek Fire, July 26 and 27, 2015: DFPC received dispatch at 1700. The fire was located half way between the border of Colorado and Rock Springs. The video was taken by Mike Miller, DFPC Pilot (contract) from Tanker 831 (T831). There were 5 SEATs working on the the fire when this video was taken.The objective was to contain this fire as soon as possible.”
“Video taken from T831 aircraft in Craig, CO. DFPC crew dropped water to assist firefighters on the ground fighting the Keystone Fire on July 24, 2015. Video taken by: Mike Miller, DFPC Pilot.” (The action starts at about 2:55.)
And here is a bonus — a short video from one of Colorado’s Multi-Mission Aircraft demonstrating the two cameras, visual and infrared.