...what do you guys think the end video in clear sky means?
Spoiler alert...
The story of Clear Sky takes place before Shadow of Chernobyl. In CS you play as Scar and you are tasked with hunting down a man called Strelok, who had found a way to protect himself from the psionic powers which prevented Stalkers from reaching the nuclear power plant, which is where they believed the most valuable artifacts to be located. Your job is to destroy Strelok's psionic shield, which you do, using a special weapon given to you by Lebedev, leader of the Clear Sky faction.
Right after incapacitating Strelok, a massive emission disables everyone around the power plant, including the now-unprotected Strelok. The ending shows Strelok (along with other Stalkers), being brainwashed by the C-Consciousness (a hive-mind consisting of 7 soviet scientists), probably with the aim of making the Stalkers forget about the experiments being conducted in the Zone by said hive-mind. The camera zooms in to reveal the letters S.T.A.L.K.E.R. on Strelok's arm.
At the beginning of SoC, you as the player, are discovered unconscious and suffering from amnesia, with these same letters on your arm and a PDA with the instructions to kill Strelok. During the game you realise that you
are Strelok. The hive-mind, thinking that Strelok was not brainwashed (they didn't know his psionic protector was destroyed), accidentally brainwashed and instructed Strelok to hunt and kill...well, himself! Awesome.
Realising that you don't need to hunt yourself, you decide to rather search for the wish-granter which, unbeknownst to you, is another experimental device built by the C-Consciousness. Depending on how you decided to play the game and conduct yourself in the game world, you are presented with 6 or 7 different endings. Call of Pripyat picks up directly after these events and assumes that you decided to disable the wish-granter. Playing as Major Degtyarev, you get to meet Strelok near the end of the game.
Makes sense?
Really hope they decide to include Strelok in one way or another in S.T.A.L.K.E.R. 2. Maybe Strelok, Scar and Degtyarev will all play a part?