Question: Today I opened a social network and saw that one of my coworkers, let's call him Bob, posted a piece of source code of one of our projects.

The quick video is blurry, so it's hard to actually read it, but not impossible.
IANAL but I'm pretty sure that this is illegal.

There is no way that anyone else in my company will see it since no one has that social network but for me.

As I see it I have 3 options:

* Act as if I did not see it
* Talk to him in private and make him realize how potentially bad this could end up being, for him and the company.
* Report this to my boss.

**Additional information:**

This is the first work experience for Bob and he has been working with us for less than 3 months.

My question is: **How should I behave in this situation?**

I really don't want to escalate this, but if something bad happens because of that post, and my boss finds out I knew about it, I think I would be in legal danger.

Answer: 
If possible present the video (in its context) to your information security team without mentioning who the employee is, something along the lines of "I came across this video from one of our employees and it looks like they may have accidentally caught some of our code in the video". If you are asked who the employee is, it is better for **you** and the company to tell the information security team and let them handle it.

Even if we were to remove the video content, there may be policies against the use of recording devices within the workplace (phones with video/audio recording capabilities are generally included for the purposes of these policies).

Best case scenario: all employees are reminded of their responsibilities and the employee responsible receives a soft strike on their record.

Worst case scenario: the employee loses their job and faces a civil case.

Handling the situation yourself could carry more risk than ignoring it or reporting it to the information security team. While I don't advocate ignoring it, it does provide you the option of deniability "I don't interact with x on the platform so I couldn't have seen it" (admittedly the posting of this question could reduce your ability to rely on that). Handling the situation yourself though, opens you up to the employee continuing this behaviour and you handling it, eventually you get fed up, report it and the employee throws you under the bus in desperation/retaliation.

As a bonus for one of your comments on your bosses not liking social media, this is a good example of why. People tend to forget that social media is not like hanging out with a group of friends at your home; it's more like hanging out with a group of friends in a crowded pub and you never know who is watching or listening.
The person is new to the workplace, suggesting they are quite young. I would recommend letting the manager know about it. You can tell the manager (assuming they won't consider it themselves), that a firm talking to by them now would make it clear what a person's responsibilities are in the professional environment and what is not acceptable despite the ease with which people post all sorts of personal information online.