Bungling Scott Curtis, 45, was recorded by the device saying he sold “gear”.
He was captured making the reference as he conducted Class A drug deals from his yellow Ford Focus.
Merthyr Tydfil Crown Court was told that police caught Curtis when they pulled him over in September last year.
He was seen throwing small bags of cocaine and heroin out of his car window as cops pulled him over.
Officers then found cannabis plants at his home during a search before they came across his car’s dashcam.
After searching through the footage, they discovered two hours of clips showing some of his latest drug deals.
In one scene he was seen polishing his car before answering his phone and being heard saying: “I don’t do Valium, gear I do,” and agrees the price “three for 25”.
The drug deal was then recorded in full view of the camera.
Curtis, from Aberdare, South Wales, was jailed for two years and six months after pleading guilty to possessing cocaine and possessing heroin with intent to supply and producing cannabis.
Detective Constable Steve Woolley from South Wales Police said: “Scott tried his best to get away with his crimes. He threw drugs from his vehicle and then claimed that it was all for own personal use.
“But when we played back his own dashcam footage, I don’t think he could quite believe it himself.
“Initially he replied no comment each time he was given the chance to explain what was going on, but so good was the case against him, he pleaded guilty to all charges and will spend a considerable time behind bars.”