@dut412 Thanks much! As a new Linux user, I was also having this problem in Ubuntu and eventually figured out what you were saying.
To expand on what you said, if you open the Settings (either from the drop down menu in the upper right corner of the desktop or by searching the Activities), then select Printers, you can add any printers that are missing. After doing that, select Applications in the Settings dialog, select Opera, then turn on the "Print documents" setting.
The Opera specific Applications settings was the part I was missing.
Unfortunately, the "locate" command does not seem to work in Crostini (the Chromebook terminal).
Well, guess what @sgunhouse and @leocg ... I got this to work using the video and some nuggets you fellows gave me about a week ago ... Hallelujah, my Opera on Linux/Chromebook has videos in Twitter and elsewhere now!
Still an interesting error
$ opera --disable-extensions
[4111:4111:0319/112615.024234:ERROR:sandbox_linux.cc(374)] InitializeSandbox() called with multiple threads in process gpu-process.
$ opera --version
Ubuntu 18.04.05 LTS