With regards to IrfanView, as far as I can see its only the MRUs (under 'File') that contain any info to be cleaned. Unfortunately I can't find where they are stored and so can't write a winapp2 entry at the mo. I'll have another look tomorrow in case I'm just being blind.
You can though stop IrfanView storing this info in the options if you want. In IrfanView click Options>Properties, click the 'Misc 2' tab and from there you can untick 'Add MRUDs to file list' to stop them being stored. There is also a 'Clear' button to clear the MRUs that are already there.
(Can't help with VLC player as I don't use it)