Did you see a YouTube video and wanted to share video with a friend but the part of video that you liked was in the middle and your friend has to seek to start viewing from that point.But you could actually share the YouTube video link along with the exact time and the video starts playing right from that time and there’s no need for any seeking.

Just add the following code to the end of the video URL:  #t=1m47

For ex. http://www.youtube.com/watch?v=_Rf2eN2e2WM#t=1m47

If its seconds only then add the following code to the end of the URL #t=30s, where s is seconds.

For Ex. http://www.youtube.com/watch?v=zkTn5Ef1Oig#t=50s

You can also add the code to the video you watch at YouTube.

Source : Tubetorial