It's unlikely you'll find something wireless. It'd have to be powerful enough to compress video in real time, which requires powerful hardware.

Instead, how about an HDMI splitter and a 20' HDMI cable between the screen and your seat?

For presentations, what I do is either follow along with my own copy of the slides, or a lot of times the presenter will also share their screen with something like WebEx for remote people, which you can just log into.

If it's really something that can't be accessed like that (i.e., a video) then I've used a camera in the past and just pointed it at the screen and viewed it on my laptop. There are special purpose cameras for this (that often also act as a CCTV too) or you could just use a webcam if it's high enough quality.

In theory, wireless HDMI dongles do exist, but from what I've seen they're intended for outputting to an HDMI source (like streaming a laptop to a projector). So you'd need an HDMI capture card for your laptop too, and a splitter to split the signal to the TV and the wireless HDMI box. It's possible to do, but I think the cost and time to set it all up before a meeting would just make it impractical.

Is it a smart TV or an Apple TV? Apple TV has its own screen mirroring built in