Streaming video integration
I have used Navicast (but not a free) platform to develop a webtv module for Drupal 6. It is based on Output APIs. There are few limitation with the platform APIs that I reported. Navicast Studio a desktop application build around their input APIs used to upload video and adjust video properties. The platform has built in tagging system to categorize videos. Comments on video contents is also managed by the platform.

I used it with Flow Player API module.

I developed Web TV around my own entities.