Lets start howeever, by choosing your matte colour. What colour you want will depend on personal preference or the video editor you will be using.
] mirv_matte_setcolour 0 100 0
The command takes 3 arguments for red, green and blue, from 0 to 100. So our matte now is a perfect green, or #00FF00 as you might say if you were a pro-webdesigner. Or possibly not.
Now you choose what you are recording, using mirv_movie_splitstreams, which has 3 possible values.
] mirv_movie_splitstreams 1
This only shows the world, entities are invisible.
] mirv_movie_splitstreams 2
This only shows the entities, and the rest is the matte colour you specified.
] mirv_movie_splitstreams 3
This alternates between the world and entities, and is probably the one you'll be using more often (but maybe not).
By default MDT will do image dumping itself, so you don't need to faff around with startmovie. If you do want to do this manually, you can turn this off. MDT will automatically name your images (you can specify filenames) as well as take numbers and stuff like that. Plus it can do snazzy effects like depth dumping.
What, did somebody mention depth? Oh yeah, using mirv_movie_depthdump 1 you can also dump the depth buffer to tgas too. This is a representation of the depths of the image, the nearer to the observer something is the darker it'll be. Generally this will look very white indeed, except your weapon which will be pretty black. You can alter the range on your favourite video editor to make the difference much more pronounced, and use this for cool effects (such as depth blurring, I'll write a guide for that if asked). Here's a quick example of the sort of effect: clickville.
Right where were we? We'll set the filename in order to keep things nice and organised.
] mirv_movie_filename "that_scene_with_chicken"
There's a few more cvars you might want to mess around with:
mirv_movie_entityonly - setting this to an entity number means that its the only entity in the entity stream and the only entity not in the world steam.
mirv_movie_swapdoors - use this to pick whether doors are in the world or the entity streams
mirv_movie_swapweapon - same as above but with your player's viewmodel (the gun coming out your screen) instead
Finally use +mirv_recordmovie or mirv_recordmovie_start/mirv_recordmovie_stop to start the effects going (and the custom tga dumping if set).
A tutorial on chromatography would be handy really for post-plugin trickory, but beyond the scope of the plugin manual really!