There have been so many changes to the youtube api in the past years, it’s pretty hard to determine the google search results to be true or not. After all, the current solution is to
a) escape ‘&’ with ‘&’
b) add that to the existing url ‘&fs=1&hd=1’
which will then make the video url look like this
http://www.youtube.com/watch?v=iFal7Pyj_hk&fs=1&hd=1
easily puttable into the youtube downloader.