I was excited when Fuji released the X-Webcam software for Mac, but having tried it, I was disappointed. Reasons for my disappointment:
Resolution: From my X-T3 it is only 1024x768 resolution, with black bars at the top and bottom of the transmitted image. Selecting the 16:9 frame from that, which Zoom can do, gives a 1024x576 image, the same vertical resolution as standard definition PAL.
Somewhat awkward operation: To change settings, e.g. try a different film simulation, I needed to unplug the USB, change the setting, turn the camera off, plug the USB back in, and turn the camera back on.
No sound: Only video is transferred to the computer. This wasn't a big problem for me, because I have a Rode VideoMic NTG, which works brilliantly as a computer microphone when plugged in to USB, which also powers it. But it is natural to want sound as well as video to come from the camera.
Buggy operation of the software: I wanted to join a work team meeting via Cisco Webex with my video turned off (and without the X-T3 plugged in). Pressing the button in Webex to turn off video (X-Webcam is still running, showing a FujiFilm still image) caused the mouse pointer to turn into a beachball and the software to become unresponsive. In Zoom I could turn off the video OK, but couldn't turn it back on.
I decided to look for an HDMI to USB capture card. The computer I have, which is connected to my TV, is a mid-2011 Mac Mini running High-Sierra (the most recent version of Mac OS compatible with the hardware). It only has USB 2.0, but that should be fine for a webcam. I had heard that video capture cards were expensive, and in short supply, but I found this neat, little USB 2.0 dongle that sounded like it would work (image attached). It is unbranded, and seems to be offered by a number of different resellers on Amazon. One comes with a short USB extension cable, which may be useful. At £17, I thought it was worth a try! I think capture cards get expensive if you want features like 4k output and zero latency HDMI passthrough, things that game streamers want.
The dongle has a maximum output of 1080p30, but that's also the maximum that I think you can expect videoconferencing software to work at. It works perfectly, and I'm really happy with it. It seems well made, with a strong, aluminium casing. It has no settings, and just appears in menus as a device called "USB Video". It outputs M-JPEG, 1080p YUV encoded JPEG images at 30 fps, which is a standard format for a USB webcam. It works perfectly in Cisco Webex and in Zoom - I can turn video on and off. When the camera isn't plugged in it transmits a test pattern (attached) which is a nice behaviour.
Settings on my X-T3:
Set recording to not save on internal SD card. The camera is plugged into the dongle via a micro-HDMI to HDMI cable, which you'd need to buy in addition to the dongle.
Resolution: 4k 16:9 at 30 fps (4k 29.97 in menu). I started out with it set at 1080p30 (FHD 29.97), but there was bad aliasing on edges. Looks like the dongle was outputting 540p, and it seems it might always downscale the video. Setting the X-T3's HDMI output to 4k 30 fps I get a nice, clean 1080p image. I thought I'd give it less work to do by providing a signal which was already 1080p, but I guess a downside to not having any settings you can modify on the dongle is that you're stuck with its pre programmed behaviours.
Shutter speed: 1/60th second, for perfect 180º shutter angle and smooth, natural motion. Not something you can easily get from the average webcam.
I'm using the 16-80 zoom, which is convenient for adjusting framing. I leave it set at f/4 since my flat isn't brightly lit.
Auto-ISO and auto-focus. You could set both manually if you know your lighting isn't going to change during your call, and you're not going to move around.
Adjust other settings, such as film simulation, to taste.
On a Mac launch QuickTime Player, choose File > New Movie Recording, select Quality > Maximum from the popup menu to the right of the record button, and you can check what the video looks like at its best before it's sent over the internet, where nasty things may happen to it!
I also bought this dummy W126 battery and cable which I plug in to an Anker power supply I already had, so I don't have my battery running out during a conference call. More expensive than the capture card!
Hope you find this, my first post, useful,