2012-03-01T00:00:29Z 1360015279 mychannela 0 asdfasdf:0
2012-03-01T00:04:23Z 0728509428 mychannelb 6 bsdf92c1:6
2012-03-01T00:01:23Z 0516050342 mchannela 20 b00sdfsdk0:19 b0dfgdfgk1:1

... where the columns mean
timestamp userid channelid total_duration ... then a sequence of {itemid}:{mins} for each item viewed in that session of viewing the channel. These will sum to the total_duration.