A reposting of the instructions for embedding a YouTube video in a forum post...

. In YouTube, go to advanced settings and check the "Allow embedding" option.

. select and copy the youtube link (the one in the format youtube.com/watch?v=xxxx)
. in TM, switch to "Full Reply Screen" for your post
. click the "Enter a media tag" button, 5th from left.

. click the bottom option "YouTube Video"
. in the pop-up box, paste in the URL

. IMPORTANT: remove the s in https to make it http
. Press OK

The video then appears within the post (all being well)...

1980 Royal Ivory 4/4 4-seater. B4771