During flight over east Russia (about 2 hours), internet service might not accessible. About the internet speed, I've never experienced yet but I heard that it is not that as fast as at home. At home (in Korea), it is usually 2~10Mbps while CBB is only about 150Kbps (this is optimized speed, so maybe less than 150). But they say that doing messenger or searching simple pages are OK
. I think some heavy pages like a.net homepage will take more than 10~20 seconds to open it all.
I guess you will be able to enjoy AVOD at all classes on 081/082, check it out through your local KAL office. If AVOD is available on those flights, that will be much funnier than slow internet.