Just happened to me too, won my first cup final 6-2 tried to upload video and it hung at the encoding video bit. Needless to say I lost 1-0 when I tried again from a previous save
Dunno if it helps, but I tried to link FM (at different times) to youtube in both the preferences screen and when I try to upload the clip after the match has finished and both times it presents a code that I have to copy and paste somewhere for a split second (don't get chance to read the entire message let alone copy the code). I'm assuming I have to paste this code in my youtube account to validate the upload process? Its literally blink and you miss it, gone before you get chance to copy it.