anyone know how I could uploud videos or big shots on forza 5

you would use the Game DVR function. go into the replay and start recording a clip (up to 5 mins) then go into upload studio and upload to onedrive.

Just for my general info; you’ve had the One roughly 6 months now and although FM5 seems to be the only game you’ve played on it, have you tried reading the official Xbox-forums and the tutorials Microsoft put online concerning the usage of the One and all its features?