Mwahhhahahaha, welcome to the dark side :D, I actually have a video clip, which is ALL of Castiel's scenes since he entered Season 4, butit is a humongous 207mb and lasts for 30 minutes, but it would give you a good idea of ho slashtastic he is with Dean without having to watch all the episodes. I hae uploaded it to my mrgaupload account (link below) if you want to download it and have a look
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http://www.megaupload.com/?d=CKHIHZCJ