2) Upper right corner of comment box, click "Attach" button
3) Choose "A YouTube video"
4) Paste entire URL *from your address bar* (do not use 'share' link under info box on YouTube)
5) Click "Submit" (in the 'attachment' window)
6) Add a comment describing video or pointing to time index/indices where feet can be seen
7) Click "Submit"
As @T97 said: "That's how you do it.) "
Easy enough? Hope this helps.