On android they did state the size on the page thats now been dropped as well
SkyGo on PC also had the file size till recently but that silverlight and was limited to ~1.4Mb/s for downloads...
an approx guide
H264 is a lossy codec It only uses bit rate when there are actual changes in the picture and colours so there is not fixed size... Lots of black lowers the file size..
But for a US 60min time slot show which is actualy only ~40-44Min with out adds you can require ~400MB to 600MB
Films are still limited to the same bit rate but most are still cinema ratios so Black boarders save file size...
So H264 reduces file size alot, some 90 minute films can be only 800MB as scene changes are not active a lot.
In films Over 2 hour films can easy push over 1.3GB...