Hi Oded/Nir:
There seem to be a few issues specifically when YouTube videos are uploaded onto the forums and we folks end-up posting a few times over.
Here's how I see it (I could be very very wrong):
1) When a user tries to link a video that does not contain youtube.com the post goes through, but the video doesn't show up.
An error message could resolve this issue.
2) When a user tries to put in a link that does not direct to a video - for example, could be the link to a channel, a search result on youtube etc., the post still goes through...
An error message that asks the user to specify a link that directs to a video could fix this issue.
Globally, this could also be avoided by allowing users to edit and/or delete posts within 15 or 30 minutes as most such issues are realized almost immediately by us forum users, but the post is already out there.
This may also avoid misunderstandings and ensure world peace.