). Just post the URL as normal and add the time to the end in this format: #t=1m23 (for 1 minute, 23 seconds in)Examples:
5 min, 41 seconds into "http://www.youtube.com/watch?v=BYgPE91prbM":
http://www.youtube.com/watch?v=BYgPE91prbM&#t=5m41
Better yet, 5 min and 59 seconds in:
http://www.youtube.com/watch?v=BYgPE91prbM&#t=5m59
http://www.youtube.com/watch?v=BYgPE91prbM&#t=5m59
It only seems to work if you watch it embedded (or post an actual link with #t=1m23).
(posting this in BW because it's most relevant here :p)