Viewing Time

We were having an internal discussion here at Narrowstep about viewing lengths amongst online video providers and it's surprising how little meaningful data there is in the public domain on this. The best I could find was this table from comScore:

The disparity in figures seems to indicate that something is very wrong with these stats - why do Heavy average 3 mins per session and Veoh 104 mins ?

At Narrowstep, where we specialise in long form, our figure is 109 mins per viewer.

This is a crucial statistic for the commercial viability of these services - 4 mins means one ad; 104 mins means 26 ads.