Have you tried to even press the little YouTube button and putting the code in between them. It should look like:
[ youtube] blahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblah
lahblahblahblahblahbl
ahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblahblahbl
hblahblahblahblahblahblahblahb
lahblahblahblahblahblablahblahblahblahblah [ youtube]