Probably the silliest suggestion ever, but here I go. How's about having an on-site data-base of all usable codecs, both sound & vision, with download links to said codecs. ( if not stored on the dev's site..)..
We do have guides on how to treat each file-type, with links to relevant codecs,
but some codecs require licenses to use, and we're not presuming to collect codecs - we do presume to play the media right with only open source codecs and with the highest quality.