As a spectator you obviously have a 3 minute delay to avoid "ghosting".
But a lot of Summoner Spells and even some Ultimates have a higher cooldown than 3 minutes.
So for example, if I as a spectator see, that someone has flash in 180 seconds, I know that he just got it in the "real game".
Is it forbidden to spectate friends and tell them stuff like "hey, their top will have flash up in 30 seconds" (because on my screen, they have it in 210 seconds)?
Or saying where control wards are (because if you see them, there is a possibility that they will still be there in 3 minutes)?
I mean theoretically your friends could time the summoners themselves. But they couldn't consider CDR-Boots or -Runes or know, if someone flashed or healed while they didn't had vision on them.