Interactivity is the name of the game when it comes to videos and the tools Omnisio provides. YouTube added their annotation feature to the site when Google acquired the privately-held company.

The recently announced move takes Omnisio from startup to corporate citizen in a short span of time. Omnisio publicly debuted in March 2008. A purchase price was not disclosed, though TechCrunch suggested an all-cash $15 million offer sealed the agreement.

Users of Omnisio’s features on YouTube will be able to add comments to videos while they watch. Omnisio also offered a way to perform some editing, where people can pull clips out of other videos, mash them into a new one, and post it on a blog or site.

YouTube mentioned the Video Annotations, and posted a brief how-to page about using the new tool. Omnisio’s features go beyond commenting and mashups, allowing users to create slide shows alongside videos (how corporate) and to markup videos for easier navigation.

It’s a nice win for YouTube’s users, and a modest price for Google to pay to quickly gain the features and the engineers behind them. Omnisio doesn’t address Google’s needs for monetizing video at all, which is the only reason why one might question buying Omnisio at this time.