Hi there!
I had the same problem. You can use the laptop camera if you want.
There are some ways to do it. I'm using webcamXP and dual monitor setup.
So how does this works?
Plug both your desktop pc and laptop to a router. Let them be on the same LAN - Local Area Network.
(Don't forget to do this on your laptop and not on your desktop pc)
Download and install WebcamXP
http://www.webcamxp.com/download.aspx
Fire up WebcamXP.
You'll see some buttons on the left.
The first button is 'Monitor' where you can modify the camera brightness and other settings.
Second is 'Web / Broadcast'.
Click on 'Web / Broadcast'.
To the right you'll see the "Internal web server is not running." message.
If you click on 'Activate' next to it you'll see "Internal Web Server is running." which means your laptop streaming it's webcam with webcamXP software.
Now you'll need to know what's your laptop's local IP if you want to use it on lan (It's recommended).
You can go into the network settings of your laptop and set it by yourself if you'd like or you can find out what's your laptop LAN IP by making a txt file and type these into:
ipconfig
PAUSE
Now save the file and rename the txt to bat. It will ask if you really want to rename it click yes.
Run the file you'll see a bunch of stuff there.
Search for IPv4-ADDRESS.
In my case it's: IPv4-ADDRESS. . . . . . . . . . . . . : 192.168.0.69
Or if you look at the bottom right corner you'll see "
HTTP ONLINE @ http:// blablabla" and if you click on it the webcam stream will appear in a browser.
Now click back on the webcamXP software and look for 'Connected users' (it's in Web / Broadcast).
Now you can see the laptop IP Address. Here is an example:
Id | IP Address | etc
2 | 192.168.0.67 (this is the desktop pc)
4 | 192.168.0.69 (this is the laptop) You'll need this number.
Now open up a browser like google chrome.
Type those numbers to the top (like where you see:
http://obsproject.com/) then press enter.
And there u'll see the laptop webcam's stream.
Now do a window capture on that part of the window where you see the webcam stream.
Move it to your second monitor like you do with twitch chat (if you do it like that).
And it's done. You can resize / reposition it anywhere you want in OBS with Edit Scene.
Don't forget to click on Preview Stream because you can only edit the scene if you livestream or preview stream.
If you have further questions let me know.
Hope this helps.