The followintg pertains to advertising subscription content sites online:
After much trial and error with various styles of video advertising, I am finding that the best for direct response make use of videos as the ad units themselves.
Look for hub/portal/community sites and networks where you can pay to upload clips/have a channel on the publishing site to promote/drive traffic your own content site.
More specifically, look for the sites that allow their entire video player to be linked to your advertised URL. Rather than focusing on the publishers who just give you banner and text link spots around the player, the idea here is that consumers who view your 3-5 minute teaser clip and want more may be trying to click on the player anyway, thinking it will link to the rest of the video, whether on the site they landed on, or on yours, where the subscription offer exists.
The theory has been put into practive across multiple genres of entertainment sites with output in the form of both increased traffic and direct response, aka sales.