I've never tried feeding the freeze dried variety, but my fish absolutely love the frozen ones as a treat. If you do get some, it's a good idea to put the frozen block into a net and run some lukewarm water over them until thawed. It'll prevent any damage to your fish and also gets rid of any gunk.
Soak the freeze dried ones in some tank water for at least 15 minutes before feeding them to your fish. Rehydrating them is necessary as it prevents them from causing intestinal blockages and constipation.
i have been feeding my discus fish these blood worms for 4 months now. dont want to jinx it but they are loving it. and so are my black ghosts and eels. if you want to save alot of money on them, buy them from the link i provided. i paid 30 dollars and its like a year supply for me lol. the way i feed them is i put a small amount (depending on how many fish you are feeding) in a shot glass of fair temperature water, leave it for about 3 minutes then pour it in the tank.
Yikes...it would run me $40 to have $30 worth of frozen bloodworms shipped. 16 ounce flat packs go for about $9 at the LFS, so I could get the same amount from right down the street for $45 and avoid the typical risks associated with having frozen foods shipped.