YouTube claims Viacom has been "continuously and secretly" uploading its own content to the video-sharing site for years.

YouTube's Chief Counsel Zahavah Levine made the comments in a blog, following the unsealing of case documents from 2007 relating to the lawsuit Viacom bought aginst Google.

Viacom sued the search engine for $1bn in damages for hosting infringing content on YouTube.

Levine also fired off a clever snipe at "Viacom's own practices".

Levine alledges that while openly complaining about the presence of infringing, Viacom-owned video on YouTube, the media giant hired no fewer than 18 marketing firms to upload content on the video-sharing service.

Levine even says that those firms added a handful of impurities to make the video look as though it were taken from a second-hand source.

Then the firms would send out their employees to create anonymous YouTube accounts under fake email addresses and upload videos from their local Kinko's copy center.

The rest of the alleged escapades are a little more innocent and a little less cloak-and-dagger.

Levine claims that "Viacom routinely left up clips from shows that had been uploaded to YouTube by ordinary users", noting that the president of Comedy Central and the head of MTV Networks wanted clips from The Daily Show and The Colbert Report to stay on YouTube's servers.

Sometimes Viacom would even issue demands that its own videos should be taken down, only to admit that it had made a mistake.

YouTube also points out that Viacom "tried repeatedly" to buy YouTube despite having framed the site as a malevolent entity no different from Napster, Grokster, or The Pirate Bay.

Levine's closing remarks promote YouTube's own Content ID system, which allows content holders to scan videos and decide if they want to "block, leave up, or monetise" infringing content found on YouTube.

Then Levine wraps up by stating YouTube and Google's position on defending Digital Millennium Copyright Act (DMCA) rights, technological progress, and freedom.

While there's still no end in sight to Viacom's case, it remains a fascinating struggle between traditional media, new media, and the methods by which each profits off the other. Whether or not Levine's claims are true, three years on, Google shows no signs of backing down.

See also: YouTube rolls out automatic video captioning