Checkout this app for watching videos on your TV, it is called Web Video Caster http://webvideocaster.com
I found this app when researching ways I could cast the ustvgo from my converted fire hd 10 tablet to my new Samsung tv.
It seems casting has become an issue with Amazon and they make it difficult to do on some devices. On my windows 11 laptop there is a built in caster for websites, but on my tablet browser that feature isn’t there. This Web Video Caster solved that issue.
It is a free app, but I went ahead and bought their $3.99 lifetime sub, but it is not necessary to do so. I just like supporting developers that help us cord cutters to do what we do.