I wanted to add in a word of further explanation about why I feel so strongly about not searching or browsing randomly online, especially when feeling bored. Even though the basic idea is obvious to anyone here. 
By definition a person who is "feeling bored" is person is feeling unstimulated and looking for stimulation. 

And there are 2 points I would share. 

1. Lust provides stimulation better than a lot of other things. So when a person starts looking to be stimulated and there are millions of potential websites or videos to search he will very likely be pulled by his boredom, to the one that has the promise of a little “tickle” of desire, because it’s more stimulating. And from there to next one, in which the tickle is more pronounced, more stimulating. One foot after another stepping along that slippery slope… I have a good filter, but...

An honest look back at the list of sites in one's search history, seeing at the end of the night how one thing leads to another - can be a very learning (and painful) experience... [I learned this lesson a long time ago, not recently, BH.] 

But there is a much deeper point, I think. 

2. The actual state of “going looking” to be stimulated is negative, I think. 
This point is subtle and is about a Madreiga too, I think But I’d like to elaborate, to put the concept out there. … 

If I’m sitting back and saying “I’m dissatisfied because life isn’t interesting or satisfying or engaging enough - so show me something to stimulate and interest/entertain me”. That’s a state of being passive about living, and looking for the world to service me. To stimulate me.  I think being that way opens a person up to things that aren’t great. Being there is already halfway there to going onwards to look at an image that will get my heart rate up. I'm saying something strong - this state itself puts a man into the posture of pornography.

I can’t really imagine a great person such as Rav Moshe, or any of my Rabbeiim, or my father shlit"a, for that matter, saying: “I’m bored. Make me feel good”. A purposeful, active  posture of living doesn’t have room for being stimulated by YouTube. 

A person who is comfortable with himself, with his thoughts and essence and feelings, does not shun inaction. He isn't bored or repelled by just being himself. And when there's a lull in the action, if he does not need to rest, he finds something positive and meaningful to think and act upon.   

Yes, this Hashkafa is firmly against the entire culture of TV, movies, entertainment, YouTube, news, and sports. Maybe it’s a little extreme to put fully into practice, and not relevant for an average guy (like me). But I’m sharing it for the concept, and for ways that can be applied, mostly for myself . 

I personally, have BH mostly successfully eliminated using the internet for recreational purposes.[משום מעשה שהיה , obviously. And I aint proud of that.] I don’t know if other people can do that. But for me it has been a complete game-changer.

I still get bored and look for things of interest. I’m not past that. I would like to get all the way there. For now, I am taking the step (among others) of not looking for stimulation by browsing or searching online bl"n. If there's something specific I want or need (including GYE) I will go get it (with a filter, obviously). But I don't wander. Because scary monsters live there. Some of them have even been known to wear my face …

And also, I would much rather be a little bored than full of that empty self-loathing for how I spent the past hour, even if I didn’t “cross the line”.