Hi, I was looking this app some time before. I installed deb package using Ubuntu Software Center, in Ubuntu 18.04 LTS. I can hear audio from searched videos, however I can not watch the video, it just appears a green screen at the right side.
I am answering myself :-)
To inactivate hardware acceleration on ubuntu 18.04 I had to remove the gstreamer acceleration library (gstreamer1.0-vaapi) that is used by minitube for video rendering.
Then relaunch minitube and it should work.