What did you actually give him? What does he know about you? From an IT perspective, I can just say that he needs to be one hell of a hacker to actually find you. He could hack into a relevant database your camsite uses to store your data. And by hacking I do not necessearily mean the approach presented in TV shows or movies. If there is a possibility to do that at all, it would be via social hacking - he might work there himself, or maybe compromised a person who has access to your data. Social hacking is the most effective way to compromise any network - I am managing an 800 user network and that's what I fear most.
Another way is to compromise your PC or the device you're streaming from. If you had a technician repair it or something, or if anyone you don't know had access to your device - format your HDD/SSD, better use data shredder software and start from scratch. Even better, get a new SSD and destroy the old one.
Actually, this my most important advice: As you could also have been infected with some kind of rootkit, keylogger or backdoor/trojan software, I would NOT stream from this device again. If you have to turn it on, do so while offline! No ethernet cables, no Wifi! Get a new SSD/HDD, reinstall Windows or whatever OS you use. Do it yourself if possible. Have a person you TRUST configure a firewall (best if that's an extra device, like a hardware firewall. Your home router should be able to do that, if it's worth a penny) so it only allows packets/traffic relevant for streaming. Don't run unneccesary software while you stream. At the very least, monitor your network traffic to find out if there are things going on that you can't pinpoint to your streaming software.
Also, I hope you never gave him your phone number, you would be actually traceable. It is not easy for normal people, but you never know who you're dealing with. He might even work for some state organization having access to communication data.
Actually, I think this is just a blunder. All the things he could do to actually find you are highly illegal and require exquisite IT, programming and networking knowledge. I think he's just an asshole trying to scare you. Still, listen to me and get your streaming device in order. At the very least, REINSTALL from scratch. And use a fresh USB Drive to do it!!
Heed my advice and talk to someone who has experience with IT security!