This means two things
1) the owner of that site might spread malware infecting many many people.
2) the ISP also might do that.
Ubuntu Version:
Firefox Quantum version:
The URL: hxxp://ciscobinary.openh264.org/openh264-linux64-0410d336bb748149a4f560eb6108090f078254b1.zip
The zip contains these two files:
3f201a8984d6d765bc81966842294611 libgmpopenh264.so
44aef3cd6b755fa5f6968725b67fd3b8 gmpopenh264.info
The info file:
Name: gmpopenh264
Description: GMP Plugin for OpenH264.
Version: 1.6.0
APIs: encode-video[h264], decode-video[h264]
So there is a remote codec loading system that is unsigned and unencrypted, I think is good to be aware of it.
In this case the shared library is a video decoder, but it would be a vector to distribute malware o spyware massively, or an attack vector for a MITM attacker.
More info