This has been going on for years now, since I was ten. I looked up videos of girls from video games, and I enjoyed it. I felt horrible afterwards, though. I thought I was the worst Christian boy on the planet.
Last year, I learned what sex was, and I was completely grossed out by the idea. I was curious what it was, though, and I looked up "sex" on YouTube, fully aware that it would bring up some inappropriate content. Sure enough, I clicked on a couple videos of people kissing passionately. After a couple minutes, I stopped, and felt horrible from the next week.
The worst time was when I actually sought out a video of a pretty actress. It showed her naked, kissing a guy. I quit it after a minute. I believe that was a sin.
The urge to look for those videos also strikes me when I'm watching something completely normal, and then an arousing ad plays before me. I looked up whatever was in that ad quickly, not even sure what it was. Again, it was another kissing video.
This is not an addiction, thank goodness, and I will never look up porn. Was looking up those videos a sin? I feel disgusted in myself for looking up those things. I have since stopped searching for them, or if an arousing thing appears I close my eyes and try to fast forward it.
Thank you for your time.
Many times Satan likes to blur the lines between righteousness and wickedness. He knows that many people will not consider something sinful if aren't certain where the crossover point is. For example, I've talked to boys who are certain that intercourse is a sin, but they aren't firm about the things that lead up to intercourse, such as inappropriate touching, lust, or lewd behavior. The result is that they get caught up in these sins because they tell themselves, "at least we're not having sex."
The reason pornography, depictions of people having sex, is wrong is because encourages the viewer to lust for what forbidden (having sex outside of marriage). But that sort of lust can be generated by other things. Inappropriate clothing or inappropriate behavior can get you aroused and desiring the sex that these things can lead toward. While they weren't pornography, those videos were causing you to desire sex without being married, so they would be wrong because lust is wrong. "For this is the will of God, your sanctification: that you should abstain from sexual immorality; that each of you should know how to possess his own vessel in sanctification and honor, not in passion of lust, like the Gentiles who do not know God" (I Thessalonians 4:3-5).
While it is hard to avoid inappropriate images in the world, you are handling it the correct way. When something unexpected comes up and causes you to start feeling sexual, look somewhere else. Be like Job, "I have made a covenant with my eyes; why then should I look upon a young woman?" (Job 31:1). However, don't use these events as excuses to continue the temptation.