The feature you are looking for is "clean HDMI out".
For most cameras that can record video, if you connect the HDMI output to an external video monotor, what you see on that monitor mirrors what you see on the camera screen -- with all the shooting information being displayed. While the shooting info is helpful when shooting actual video, it's no good for streaming because all that info will show up in your stream. If the videos aren't "live" and you can record to camera before posting... the recorded video wont show all that info.
Some cameras off "clean HDMI out" which means you get *just* the video information with no extra info overlaid.
There is another caveat. Since you are not actually "recording" with the camera... but using it like a webcam to stream stream the video so that something else can display it... the camera *thinks* it is idle... and will likely sleep the image sensor after a few minutes of not being used.
I'm unaware of any of the current "mirrorless" bodies offering this. You can get it in the 7D II, 5D III & IV, ID X II, (but these aren't "mirrorless" cameas) and I think all of the EOS-Cinema (EOS C) series cameras.
Most cameras designed primarily for video will do this. But these are cameras designed for still photography and happen to be able to also do a limited amount of video ... not quite the same as having a camera made primarily for video.
The EOS M50 *might* work for you. (Frankly, I'd try to rent one and test it ... before buying.)
Some of the Panasonic Lumix can do this (specifcally the GH5 & GH4 ... but most others cannot.)
BTW, for many cameras, to save space, they use a micro/nano HDMI port instead of a full size HDMI output port... which means you need an adapter.
Tim Campbell
5D III, 5D IV, 60Da
