On the "select additional tasks" page, when it asks me to choose which formats I want to decode with ffdshow, is it saying "any video formats selected below will use ffdshow by default for decoding", or does it mean that those are the formats that it will function with?
I don't want to use ffdshow as my standard filter/codec, I only am installing it to use SVP in MPC-HC, and I don't want it being used or being active unless I manually switch ffdshow to be on.
Uncheck all if you do not need ffdshow as decoder.
I think I do though, that's what I'll need for SVP, I just don't want it to be enabled for default for all my video players if I check those off.
You don't need the decoder. You only need to install the ffdshow "raw video processor".
MPC-HC options > External Filters > Add the ffdshow raw video processor and set it as preferred.