The old forum setup had a video attachment button in posts, and I could post any song or speaker talk I was referring to from Youtube. I've not seen this so far when I've looked around the new forum. It's probably just some setting I'm unaware of so I'm asking.
Yep it's in the third box if you start from the right end, there's a film icon. Click that, select youtube under video type and paste the link.
And to clarify for anyone seeking to do this:
1. Go to User CP
2. In the left menu column, click on Edit Options
3. On the bottom right of this page, it'll show "board style"
4. The YT addition feature is found in the "Use Default" mode, or in "Square".
I had been using the "tc" style, but it does not have these features.