disallowed characters - Youtube embedded link

[eluser]jmadsen[/eluser]
I am posting a link via ajax - everything seems normal, but...

any idea why this works:

http://www.youtube.com/watch?v=eQsmq3Hu9...grec_index

but not:

http://youtu.be/eQsmq3Hu9HA

I get the old "disallowed characters" error :-(