Find a you-tube (or similar) version and copy the URL. Go to the reply box at the bottom of the CF screen. Click on the icon for "media" (the page with the bent corner, two icons to the right of the smiley) and paste the URL on the line it give you. Easy peasy.Wish I knew how to link/post it-Frank Zappa's "Watermelon in Easter Hay" is awesome.
OTOH - if you're on a mobile, I have no clue how to do it!