Here’s how to start a video playing at YouTube.com at a certain point of time by using a “#t=” at the end of the URL, and then a time in the format of e.g. “1m45s”: www.youtube.com/watch?v=1bibCui3lFM#t=1m45s

Google Video has a similar way to link within a video: add #XXmYYs to a URL. YouTube implemented another feature from Google Video: when you mention a time value in a comment, YouTube automatically creates a link that takes you to that sequence.

Source:→ TechCrunch