ayana's Journal: MSN Messenger blocking Youtube links

I find this rather interesting - just today, I tried to send a Youtube link to a friend over MSN Messenger, only to find the message blocked, similar to how certain other messages are blocked by MSN Messenger (anything with some known malware urls, for instance). Searching on Google, it seems that others have noticed this problem - at least two forums (http://www.neogaf.com/forum/showthread.php?t=293291, and http://forums.whirlpool.net.au/forum-replies-archive.cfm/973690.html) have active threads about it, and no-one seems able to work out why this is happening. It also seems interesting that Yahoo Messenger has blocked Youtube links in the past too (http://yro.slashdot.org/article.pl?sid=06/10/10/2042248&from=rss). So, what is this? A temporary glitch? Microsoft blocking competitors? An admin error by someone at Microsoft? It would be great to know what Microsoft says about this...