[README] Add an FAQ entry for the player change in anticipation of many more bug reports

README.md

@@ -515,11 +515,15 @@ If you want to play the video on a machine that is not running youtube-dl, you c
 
 ### ERROR: no fmt_url_map or conn information found in video info
 
-youtube has switched to a new video info format in July 2011 which is not supported by old versions of youtube-dl. You can update youtube-dl with `sudo youtube-dl --update`.
+YouTube has switched to a new video info format in July 2011 which is not supported by old versions of youtube-dl. See [above](#how-do-i-update-youtube-dl) for how to update youtube-dl.
 
 ### ERROR: unable to download video ###
 
-youtube requires an additional signature since September 2012 which is not supported by old versions of youtube-dl. You can update youtube-dl with `sudo youtube-dl --update`.
+YouTube requires an additional signature since September 2012 which is not supported by old versions of youtube-dl. See [above](#how-do-i-update-youtube-dl) for how to update youtube-dl.
+
+### ExtractorError: Could not find JS function u'OF'
+
+In February 2015, the new YouTube player contained a character sequence in a string that was misinterpreted by old versions of youtube-dl. See [above](#how-do-i-update-youtube-dl) for how to update youtube-dl.
 
 ### SyntaxError: Non-ASCII character ###