Could I be fired from work if?

This is the one time I would strongly STRONGLY urge you to not say a dang thing.

You bring it up to her she is mortified [maybe an ex did it and she had no idea he was going to put it out there]

I would run from this can of worms and never mention it to any one.

MYOB: Mind Your Own Business. No you shouldn't tell anyone at work, much less the person who made this video. You would be opening yourself up to all kinds of unwanted attention and possibly embarrassing the woman and perhaps even getting both of you fired.

Once that kind of video is on the internet, it's public and it's impossible to remove. Telling anyone will do no good and can only be bad.

Besides, do you really want your co-workers and bosses to know you surf porn? Definitely NSFW: Not Safe For Work!

Keep it to yourself! You will ruin her reputation at work by telling people about this video. Also now you are admitting to everyone at work that you spend a lot of your time looking at porn! So now your boss might assume you look at porn while at work and that could cause you problems. Also showing porn to people at work shows you aren't working and are looking at porn on company time!

I say keep your mouth shut! It might just be a girl that looks like her. And even if it IS her in the video don't be that guy who outs her at work. Let someone else discover the video themselves, IF they ever discover it on their own. Because yes this could cause you problems at work if you 1) are showing porn to people AT work, which suggests you look at porn on company time and 2) you now look like you have it out for her. That you are trying to get her fired and are trying to ruin her reputation at the company. No one, especially all the female employees, will have any trust or respect for you, the guy who shows people a porn video of a coworker.

I suggest that if you don't want to cause yourself problems at work and don't want to ruin some woman's life then you keep your mouth shut and never ever tell anyone that you found a video with what appears to be your co-worker in it.

If she acknowledges the camera in the video then I wouldn't bother saying anything to her. If you approach her about this video she might think you are trying to blackmail her or have some hidden agenda. If she was stupid enough to make a sex video then let her find out on her own, or because of someone else, that there is a video of her online. Protect yourself and keep your mouth shut! Don't tell anyone about that video. Delete it from your computer and don't access it again. It is rather creepy that you have now seen your coworker naked! That's what she will be thinking. She will be horrified that YOU have now seen her naked!

Stay away from this! Don't discuss it with anyone even, and especially, if you promise them to secrecy.

Best thing to do is stay out of it. Don't say anything.

An employer can fire anyone at anytime

You should mind your own damn business

Invite her out to lunch.

You should leave it be.