[LakeGator]

This article on the Wall Street Journal site has several excellent tips for manipulating YouTube videos.

The first and most simple one is being able to start the video at a particular point in the video. This can be done by right clicking on the video while it is playing. This causes a popup menu to appear and one of the choices is "Copy video URL at current time" which will place a URL to play the video at that point in the video.

The actual URL seems to have a querystring named t (for time one would assume). To start a YouTube video at the 90 second mark the query you can just add the querystring of &t=90s at the end of the original URL. This seems like something useful for many videos posted in the various forums here where people refer to something in the middle of the video.

There are other tools for editing and testing videos in the rest of the article.