I was able to replicate and fix the problem.
try this:
$ sudo bash
# export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib
all the ptpcam commands worked, including start/stop video, take picture, download picture and video. able to set all the options.
To get that working permanently, I added it to my .bashrc and it worked after rebooting. You can also try adding it to /etc/environment (which I didn’t try, but think should work).
I’m still planning to document the full install in the future.
I think your problem is with the LD_LIBRARY_PATH
Also, I needed to run as root in my last test (use sudo bash)
I documented the full process here: