I can't imagine Samsung not revealing this issue but the short answer there is no download and no ready fix. The browser is very limited and again, there is no such download. The messages are meant for PCs, not TVs.
There are some web sites that attempt to play on smart(?) TVs but not many.
If you feel mislead by the smart TV claims, just return it. I think my Amazon Fire TV, Roku and such handles this much better.
When i try to play live streaming TV in Samsung smart hub browser, i get message that i have to download codecs for mp4, i Cant find enywhere on the Internett to download mp4 codecs, how can i solwe this problem? Thanks