To answer why people pay hundreds of dollars for a film print when they can watch the same content for free, I absolutely agree with Jimmy Owen's comparison to record collecting. For many collectors, owning the *vintage artifact* is just as important as the content. Film collectors enjoy comparing the quality of prints that they own and/or having prized rarities. And for many, setting up the projector to show their collection to friends is just a lot more fun than watching the same thing on a computer.
To take an example much older than "Say When!", anyone with $18 can buy a CD containing Bert Williams' very rare 1901 Victor recordings. But when the original records themselves turn up on Ebay once in a blue moon, collectors with deep pockets are happy to pay figures in the high three digits and beyond. The same goes for Caruso's 1902 Milan records--they're all over Youtube, but when an original 78 is up for auction--especially if it's from an early stamper--watch out!