What do you guys do with your DVD copies from Blu-ray/DVD combo packs?

[VarHD]

I guess it depends mainly on your financial situation. If your income is low enough that selling them would make a difference, then you could try eBay, always making sure that you make it clear that you're only selling the disc to avoid misunderstandings, but you've said that your collection keeps growing so it doesn't sound like you're so broke that you'd really need the pennies you'd get from such sales and let's face it - these would be pennies because full brand new DVDs in a case are so cheap right now, you'd really have to price them very low or sell all of them as one bundle.

That said, giving them away to people who don't care about HD is probably the best option if you must get rid of them.

Also, is there a reason why you keep buying standard Blu-rays instead of 4K? The 4K editions usually don't come with DVDs, instead they come with a standard Blu-ray so even if you don't have a 4K screen yet, you could still watch the Blu-ray... or the rips of the 4K discs which will still look better thanks to HDR (even on a non-HDR screen). In this case, even once you get a 4K screen, you'll still want to keep the extra standard Blu-ray discs because they often put all the extras and bonus feature on them.

[Woodstock]

I do the same thing with the DVDs as I do with the BDs, put them in a storage box with the others. Neither is coming out of the box unless there is a reason to rip it again, because I discover that I screwed up something in encoding it and have already deleted the raw rip. The DVDs don't leave the case, the digital download codes go unused.

As for keeping the disk handy to watch extras, to me, extras are almost universally "one and done" for playback. I really cannot think of an extra that I've gone back to watch, or recommended to someone as "You have GOT to see this!" in the decade I've been ripping stuff.

Note that Sony/Redbox got sued for selling off the digital download codes obtained when they bought disks. Court said they have that right.