Cast videos from mac to Samsung TV
The easiest and most reliable way is to get an AppleTV.

Unfortunately, most "Smart" TVs look to the Android OS to implement their smart functions and as such, they natively support Chromecast where you can share virtually everything between an Android phone and the TV.

Personally, I've looked for Apps that would allow me to cast to either my Sony Bravia or LG TV's with no success whatsoever.   The few apps I did find were a) sketchy to say the least b) poor quality and c) abandoned within a year or so.  I finally gave in a bought an AppleTV (32GB, smallest size).  Doing so, it allowed me to easily cast my content from any Apple device to my big screen.

And to be perfectly candid, I would welcome it if a manufacturer would simply make a really high quality, but "dumb" TV (no apps whatsoever) and let me choose what smart technology (i.e. an AppleTV) I'd like to use.