The firm responsible has been named as California-based Sambreel.
Researchers at a London based security firm have detected two video plug-ins which added unauthorised adverts into YouTube.
Spider.io exposed two programmes, Easy YouTube Video Downloader and Best Video Downloader, which placed unwanted adverts on Google’s video streaming service.
It’s been reported that Sambreel, a advertising company based in California is responsible for injecting adverts via adware browser plug-ins, which were marketed by its two subsidiaries Yontoo and Alactro.
Spider.io in a statement said: "These display ad slots are being bought today by premium advertisers like Amazon Local, American Airlines, AT&T, BlackBerry, Cadillac, Domino’s, Ford, Kellogg’s, Marriott, Norton, Toyota, Sprint, Walgreens and Western Union." .
Researchers also revealed that the ad slots injected by Sambreel have been bought by malvertisers.
A Google spokesperson was cited by the Financial Times as saying that the plug-ins violated YouTube’s Terms of Service.
"Applications that change users’ experiences in unexpected ways and provide no value to publishers are bad for users and bad for the web," he added.
"We’re continuing to look into these types of bad actors and have banned them from using Google’s monetisation and marketing tools."
Sambreel has also been accused of injecting adverts on Facebook.