The beef of the 4.5.0.18 hotfix was ffmpeg 5.0 backporting. That fixed plenty of pages reporting missing video codec.
Did try many different user-agents for the mtvuutiset.fi but didn’t find better one. This is something that we usually check first. Other plausible cause could be that our preferences are too strict and cookies are rejected right away.
Here is a forum bug for mtvuutiset.fi