The first commentary I watched was Elf, not the most educational on the technical side (although there are a few bits and pieces, particularly on the forced perspective stuff) but it's a very entertaining and informative track. One of the security guards at the Empire State Building is Will Ferrels brother!
I've done quite a few weddings in the last year (possibly ten? I do some 2nd camera stills as well, hard to separate the two...) and I've never been asked for the raw footage. Anyone who asks for it has no clue what they will actually get, unless they're also in the business and want to do an alternate edit or something.
If I was asked I wouldn't have a problem with handing it over but I would certainly charge something extra for it, and they would provide any media required. I think I would definitely also advise them that it won't be of much use to them (unless they do actually want to do their own cut), it won't look anything like the final video I've given them and see if there's anything specific they want to see. Stuff can be added in to a main cut fairly easily (if you got the shot they're looking for) and that would probably be a much tidier solution.
Anyone saying they've paid for it already - they haven't. They pay for me to come and film a certain pre-agreed amount of the day (with my business partner) and for us to provide an edited dvd/bluray/file of what we shoot. Raw footage is never part of the agreement.
One last thought, you've no idea who might end up seeing your raw footage, and how it might be presented to whoever is watching it. The happy couple might want to show off an adorable shot of darling granny with the newest cousin or some such, never mind that it was slightly soft, wobbly, not white balanced correctly and generally not usable. You could easily lose some potential future business.