Feature Request: YouTube shortcode support start time

[SilentSin]

If you right click on a YouTube video and select "Copy video URL at current time" anyone who goes to that URL will start the video at that time. After a very quick search it seems possible to use that feature on embedded videos, but Wyam's YouTube shortcode doesn't seem to support it (gives an error if I just put ?t=xxxx at the end of the ID).