Watch 60fps YouTube videos at 30fps but retaining the original resolution?

[CompVid]

Windows PC, Firefox browser.

Call me weird but I don't like watching gameplay videos at 60fps, the motion is TOO smooth and like a 'soap opera'. It irritates me.

I can download the video and convert it to 30fps using Handbrake but that's a time consuming pain.

So instead I'd like to find something that will remove every other frame 'on the fly' so to speak. I've looked for addons and Tampermonkey scripts but all that I've found have limitations - for example they reduce the fps but also the resolution. Or, in the case of addons, they are very 'invasive' and seem to require far too many permissions.

Any ideas please?

[Columbo]

Make an Avisynth script that runs SelectEven() on the video and merges in the audio. Then play the script in your player.

[VWestlife]

Set the playback resolution to 480p or less. That will limit the frame rate to a maximum of 30 fps.

[The_Doman]

Set the playback resolution to 480p or less. That will limit the frame rate to a maximum of 30 fps.

Yes, but that was not the question: Watch 60fps YouTube videos at 30fps but retaining the original resolution?
As already mentioned there are various browser extensions/scripts to block 60fps video's but then the maximum resolution will be 720p.
Google: Youtube plugin script block 60 fps

Any ideas please?

Well, a simple solution could be to set your display to 30Hz?
If you have a broadcast compatible monitor or regular TV the extra available refresh modes should show up automatically.
If not you can create custom resolutions/refresh modes and see if the display accepts it.
See for example the display refresh options of a LG M227WDP TV/Monitor:

LG M227WD Refresh modes

[Attachment 92456 - Click to enlarge]

[VWestlife]

Hardcore gamers consider a 60 Hz frame rate to be unacceptably low, and demand 100+ Hz at minimum, for faster response time... but you do you.