Fox sweet spotting BF from below? WTF?

[ECHOnce]

watching dreamhack uk while baxon vs vanity angel and the commentators brought up lovage angles which brought me to this thread

here is your fox autosweetspot four years later
https://youtu.be/3np0fhMko-4?t=5m57s

Falcon has a spot on Battlefield where he can grab the ledge before his up-b is done, Magus explained it somewhere but it was pretty complicated and I don't know where the post is <_< (he also mentioned Fox had a similar thing so that's probably what happened)

Also looooooooooooool

Some detective work, because I'd seen a thread just like this
http://www.youtube.com/watch?v=E2cOUEL9uic
http://www.smashboards.com/showthread.php?p=5543959&highlight=Falcon#post5543959

Damn, this guy had the right answer from all those years ago and didn't really get that much acknowledgement lol. Ouch