Google has begun placing advertisements inside clips on its Google Video upload site.
The video of a recent episode of the Charlie Rose show, a programme from the PBS network, is among the first to feature embedded ads that interrupt the clip being watched.
In it, the progress bar for the clip shows two blue markers to indicate the position of the upcoming ads, which are viewed when clips are embedded on other sites.
The ads are accompanied by an "Ads by Google" message and are believed to be among the first manifestations of Google's "click-to-play" video ads programme - a derivative of AdWords that involves publishers getting a split of the ad revenue when the video is played away from the Google Video site itself.
Analysts are keen to see how video sharing networks will monetise their phenomenal growth, with many having already suspected they would begin embedding marketing messages inside clips.
Though they can place textual Google Ads next to clips, the revenue for video sharing networks is thought to require advertising inside videos to circumvent the fact that users can freely embed clips on any other site.
Google-owned YouTube is not yet believed to have undertaken the move, but recently advertised for sales executives.