Just as the ink is drying on Google's $1.65 billion acquisition of YouTube, the video-sharing is threatening legal action against TechCrunch blogger Michael Arrington for creating software that allows users to download YouTube content instead of merely streaming it.

According to Red Herring, Arrington revealed Tuesday night that he had received a letter from YouTube's lawyers accusing him of committing an unfair business practice and threatening legal action if he did not cease and desist.

At issue is software that Arrington created to allow the downloading of YouTube video to users' hard drives. YouTube allows viewers to stream videos, but not save them.

Google has itself been dealing with legal troubles over copyright infringement on Google Video. And since buying YouTube, Google has allocated some $200 million toward possible lawsuits.