What I want is for the airline to provide a jack that allows the seat back display to be used by the i-phone/pad/whatever.
My last IST-TXL flight on Turkish had a USB jack that one could use to play own movies or listen to own music. Not sure if it could connect Iphones etc.
I would be a bit skeptical that -all- in-seat entertainment including on demand movies could be provided via available wifi bandwidth.
Movies etc. could be cached locally at seat. Storage is cheap and small. The WiFi link would be more command and control, announcements, updates, flight position, weather etc. None of which is very intensive on bandwidth.
New movies can be pushed out as and when needed but need not take up link capacity.