This is an
almost streamlined way to do a thumbnailed YouTube link. I don't have a PC to work with, so these are Mac instructions...
Drag/drop or paste the following template string for badged YouTube links (which you have previously saved somewhere) into the forum's posting form:
[url=http://www.youtube.com/v/VIDEO][img]THUMB[/img][/url]
On YouTube, right-click (or control-click) on the desired video's
thumbnail and copy the thumbnail's URL, which will look like this:
http://i3.ytimg.com/vi/fCC_errtFFY/default.jpg
Back in the forum, select the word THUMB in the template string, and paste the thumbnail's URL in its place:
[url=http://www.youtube.com/v/VIDEO][img]http://i3.ytimg.com/vi/fCC_errtFFY/default.jpg[/img][/url]
Then copy the video's ID from the thumb's URL -- it's the fCC_errtFFY part between the slashes in this example -- then select the word VIDEO in the template string and paste the video's ID in its place:
[url=http://www.youtube.com/v/fCC_errtFFY][img]http://i3.ytimg.com/vi/fCC_errtFFY/default.jpg[/img][/url]
...which produces a badged link like this: