So one of my good presumed straight friend at school started talking to me. I sent him a link to a funny youtube vid,he said "I hope its not gay porn,because I think its wierd (laugh),I'm not into gay porn (laugh). I never understood why he said that and I am confused... Do straight guys talk about gay porn often?
No. Does he know you are gay? If yes, he's just being a bit homophobic, presuming that a gay guy could only send him a link to a gay porn video. If no, I think he knows or at least suspecting that you are gay, and he's trying to get an answer from you to reassure himself.
I'd be like "Yep. That's exactly what it is. I figure a straight guy such as yourself could appreciate it more than me."
You could always play it up, "That's a shame, I made i especially for you." My guy friends just don't even make gay jokes anymore since I came out
Sounds like he was just having a joke. I know guys usually joke about stuff like that. However, it seems like he knows something or is hinting at something. Perhaps? Perhaps not. If he mentions and hints more along the lines of gay whatever, then he could be telling you something.