1) Unlike my other instructable where I showed How Do Upgrade Your iPod Mini With Flash Memory, you cannot simply replace the hard drive with a flash card. The 1.8" drive and CF interfaces are similar but you will need an adapter to bridge the interface from the card to the HD connector on the iPod. Finding the adapter has been the most difficult part of this procedure.
Although you can get adapters for the 4G iPod cheap on eBay, Tarkan Akdam is in my opinion the only person in the world selling a reliable adapter for the 5th Gen iPod Video. Get yours HERE.
Don't come crying to me if you use some cheap Taiwanese adapter and burn up your iPod!
2) iPod-Opening tools (non-marking plastic tools and/or flathead screwdriver). Tarkan will ship you a set of these with your purchase.
3) You will also need some hot melt glue or double sided foam tape.
4) Of course, you will need a fully ATA-Compliant
Compact Flash card. Any size will work, but you can now get 8GB cards for under $60 as of this writing. I've had good luck with Transcend and Sandisk. Check the specs, not all cards will work.
5) Oh yeah, make sure you start off with a fully functioning iPod! Don't assume that the broken unit you bought from eBay simply has a bad drive.