I only believe it because I have witnessed it couple of times in my life

I spent my entire life saying no. That I'll believe it when I see it. Then this last winter, something came into our house, stayed for a couple weeks, and that all changed. Now I am 100% positive there are things that go bump in the night, so to speak. As nuts as that sounds, it's true.

Having said that though, I don't go around trying to convince anyone of anything because I remember what it was like being on the other side. Skeptics have to experience this stuff before they believe in it. Hopefully they stay skeptics... because you don't want to have to go through what my family (yes, multiple people experienced it; sometimes even simultaneously) had to endure. 

The footage below doesn't show a ghost, but shows the manipulation of a physical object by an invisible force.

Spoiler!

Contains some extremely graphic captured video, if you are easily frightened or sensitive please don't click. I believe more scientific study is definitely warranted.

No, they are glitches like someone said but caused by the brain train to make sense of things, a noice that it isnt sure what is is... ghost.

A lot of xperiences like that ocur around funerals cause the brain is prime for it, other when you are stress tired or sleep deprived in all cases is the brain tring to make sense of things that it cant.

No, utter nonsense. There’s no logical reason for that to be true and everything always has a rational explanation, whether you have one ready or not. I have no reason to believe in things I cannot see or detect in some way. Darkness is just the absence of light, and the world is exactly the same in it.

So right as I type this I’m in the attic, and I hear cracking and tapping sounds all around me, even though there’s nothing and no-one here with me. A less informed person could be thinking this is a ghost, but no, it’s just the wooden beams in the roof that are stretching and moving.

‘Life’ is just a very complicated chemical reaction, nothing more, and when we ‘die’, our molecules will get scattered again to be used in another complicated chemical reaction sometime later, there’s no need for ‘spirits’.

People don't believe in paranormal stuff because it's never happened to them, and "ScIeNcE". Obviously videos you see that "capture a ghost on camera" is most likely fake, that also makes people become more skeptical.
I believe in it, happened to me, happened to people I know. It's not "utter nonsense", it's not "bullshit", and no, it's not our "imagination". Nothing's more annoying than people trying to explain what you experienced because it didn't happen to them and they think they know better. 

No. Not only because there's not a single piece of reliable evidence (like most people pointed out here), but more importantly because there's also no logical explanation of how they could physically exist. People used to believe in ghosts because the common idea was still that humans have a 'soul' that exists independently from the material body, but now we understand more and more how our thoughts are simply formed by chemical processes in our brain.

Something that's also become more and more clear, is that our senses are extremely unreliable. It can be very difficult for people to accept that, even when they're obviously wrong. There are cases of people who were genuinely convinced that they saw the lights of a UFO right before a crop circle was made, even when the crop circle was later confirmed to be manmade. I personally saw a bear in my garden a few years ago, despite living more than 1000km from their natural habitat.

No such things exist. There's always a natural explanation for these things and few people realize for example how much our brains and senses can trick us and "malfunction" so as to produce abnormal effects. It's just a poor understanding of how we perceive reality in the first place.
This is coupled with a somewhat natural tendency for supernatural beliefs that seems to be built in with some people more than others, these things together can be a very convincing combination.
If ghosts were a real thing, they would be an everyday occurrence and everyone would see them equally and constantly. We are members of the same mammal species with the same functions and senses, there are no special individuals with extraordinary abilities to detect otherworldly things.
I'm willing to concede that there probably is stuff going on that we are unable to detect at this time, but I don't think it has anything to do with dead people. Simply some natural processes that we can't see, just like we couldn't see bacteria until the invention of the microscope.
Samuel L. Jackson's character had a good line about this in some horror movie whose name I forget. People fear death, so they like to believe in ghosts because it means that there's at least *something* beyond death and it feels reassuring in a weird way.

I do believe in ghosts and spirits, yeah. Wouldn't bet my life savings on it tho.

There is the argument that there is no reliable evidence for it (or when there is video footage, people do not believe it), or science can't prove it. These are all valid positions.
But I will say that just because science can't prove it yet does not mean it definitively does not exist.

Human caused global warming, for instance, was happening since the industrial revolution in the 17th century. But serious research in the global warming only started in 1950-70s.  But that doesn't mean that global warming wasn't real before that.

I know enough of how the brain and perception work, not to trust those instruments for any valid observations. Until there is a repeatable experiment, I can't believe in ghosts. Yet I can't rule it out either. There are still plenty unexplained phenomena, but whether it's god or ghosts or just something natural we don't understand yet or haven't discovered yet, time will tell, eventually. I mean, not all that long ago radiation was never heard of.