To embed a Youtube vido;
Go to Youtube video you want to embed. Under the video there is a SHARE tab. Click it. A window will pop up. Click the EMBED tab. Copy the link.
Come back here in your REPLY box. Click the EMBED tab that is to the right of the INSERT IMAGE tab in the upper tool bar.
A box will show up. Click the EMBED TAGS and this will show up;<nabble_embed></nabble_embed>
Paste your video in between the >< in the nabble thingie.
This is from a computer. I've not tried a phone yet.
You meet some of the best folks behind bars.