The problem seems to be some incompatibility between OBS and VLC.
First install VLC player from the Ubuntu distribution
Now follow the following command line instruction to install OBS. If you install OBS from the distribution you will not find VLC as an option in the source list.
1. Open terminal either via Ctrl+Alt+T or by searching for “terminal” from app launcher. When it opens, run command to add the PPA:
sudo add-apt-repository ppa:obsproject/obs-studio
Input your password (no visual feedback while typing) when it prompts and hit Enter.
2. For Ubuntu 14.04 you also need to run command to another PPA for FFmpeg library:
sudo add-apt-repository ppa:kirillshkrogalev/ffmpeg-next
3. Now you can install OBS-Studio via Synaptic package manager, upgrade the software from an existing release via Software Updater, or simply run commands one by one:
sudo apt-get update
sudo apt-get install obs-studio