I know you can “cast” from a computer to a television but I’m not sure if it can be dome wirelessly or needs to be through a port.

WiFi That’s how you get videos like YouTube on your wireless computer connection.

Look into Miracast link

From their website:

Wi-Fi CERTIFIED Miracast™ enables seamless display of multimedia content between Miracast® devices. Miracast allows users to wirelessly share multimedia, including high-resolution pictures and high-definition (HD) video content between Wi-Fi devices, even if a Wi-Fi network is not available.

Miracast:

Projects content from mobile devices to automobile infotainment systems
Shares a laptop screen with a conference room projector in real-time
Streams HD and 4K Ultra HD movies from a tablet to an HD television
Shows pictures from a smartphone, computer, or tablet to a large screen television
Support a wide range of audio/video formats to extend battery life in mobile devices

1) Airplay, if you happen to use Macs and/or iPhones.

Apple AirPlay “lets you share videos, photos, music, and more from Apple devices to your Apple TV, favorite speakers, and popular smart TVs. And what you share always stays personal and private. So sit back and enjoy everything you love — in more places than ever.”

I use it to send music (not video) from iTunes in Windows to speakers.

2) Youtube
On my Android phone or Windows laptop I can choose a video and play it on a smart TV/Roku.

In the hospital we have what is basically a hdmi cable without the cable. You plug one box into the output on a device the box into the input on a monitor and then pair them. It will stream a 4K 60fps image upto about 30ft. It uses its own waveband so as not interfere with anything else and once its paired the signal is very stable.

Sadly they’re £6k a pair.

@Lightlyseared I wonder what the technology is that’s powering the box.