Opera Blacklists Tampermonkey Extension Being Installed by Malware January 6, 2019 https://www.bleepingcomputer.com/ne...rmonkey-extension-being-installed-by-malware/
I think it's safe to say that GOM Player can no longer be trusted, this is like the third time I see it being associated with malware, in the last 5 years or so.
A while back I went through a phase of testing freeware media players (on Vista). I'm pretty sure I tried GOM Player and others such as KMPlayer. I'm also pretty sure they both placed PUP's on my laptop when they updated.