Print Binary on Microfilm or Nintendo Cartridge (Score 1)

Even while the longevity of data on quality CD/DVD media will probably survive 25 years in a controlled environment, the welding part may just burn them useless.

Flash disks and memory cards are probably not a good idea as well. PDA's left untouched after a few years sometimes need reinstallation.

Printing in binary on microfilm is probably one way to go. Printing binary on paper would probably take up too much space.

You might want to consider the Nintendo cartridges. They've been around for more than 25 years, never needed any special handling and storage. Those things are tough, you can even run over them with your car, if you take away the external casing and stick the board on your NES, it's still going to be good to go. You won't probably even need to put it inside the capsule, just stick it in a plastic bag and bury it beside your capsule.