5D3 is perhaps the best currently supported ML cam for video. It's very capable - good choice. Using both CF and SD cards simultaneously, it can record at about 145MB/s, so you can get very high quality footage.

Re what we can support - it's a reverse engineering project, we can support anything with enough time ;) The very newest cams have software changes that make enabling ML slightly harder for normal users, but don't make much difference from a developer perspective. I don't see any signs of Canon trying to lock out reverse engineers. Gaining access and doing a basic, ML GUI but no features port, is not hard when you have experience.

What we choose to support: I work on the cams that I have. And the cams that I have are whatever I find for cheap, so it's pretty random. Other devs have whatever priorities they have :)

The first cam I ported to was 200D, unsupported at the time. This took me a few months to get ML GUI working (with no features enabled), and I had significant help. Now I can get a new cam to that standard in a few days in most cases. All the cams are fairly similar for the core OS. It's the peripherals that change the most as hardware improves, so this takes the most time. And the newer the camera, the more the hw and sw has diverged from the best supported cams.

The cheapest way for you to get started is to use your 5D3 - which you can do in our fork of qemu. You can dump the roms (using software, no disassembly required), then emulate a full Canon and ML GUI, which can run your custom ML changes. There are limitations, mostly around emulation of peripherals. It's still very useful if you want to improve / customise the UI.

https://github.com/reticulatedpines/qemu-eos/tree/qemu-eos-v...

Re docs - they're not in a great shape. It's scattered over a few different wikis, a forum, and commit messages in multiple repos. Quick discussion happens on Discord. We're very responsive there, it's the best place for dev questions. The forum is the best single source for reference knowledge. From a developer perspective, I have made some efforts on a Dev Guide, but it's far from complete, e.g.:

https://github.com/reticulatedpines/magiclantern_simplified/...

If you want physical hardware to play with (it is more fun after all), you might be able to find a 650d or 700d for about $100. Anything that's Digic 5 green here is a capable target:

https://en.wikipedia.org/wiki/Template:Canon_EOS_digital_cam...

Digic 4 stuff is also easy to support, and will be cheaper, but it's less capable and will be showing its age generally - depends if that bothers you.