Links taking you to a Youtube video can carry other info across to them.

For example, if you are watching in a small window that is part of a web page and click on the Watch in Youtube option, it will convey the time-point you have reached in the video so that you continue to watch 'seamlessly'. This info is all dumped into the URL.

But the forum wants a simple format ... as you've seen ... of:

ht tp://w ww.youtube.com/watch?v= xxxxxxxxxxx

Cheers,
Paul.