"Mining BitCoins these days requires a specialist rig featuring graphic cards so using low-powered embedded systems is not terribly practical.
"Kudos to camera DVRs hackers for finding something worse (ie, very ineffective cryptocurrency mining) to use them for than surveillance,"
While I recognize a low power system is not likely to find the next BitCoin, isn't there at least a non-zero chance of any system mining to be successful? Nobody in their right mind wanting to mine Bitcoins would start out by saying "let's design our engine using a 386SX CPU" but offered a bunch of them for free, wouldn't it still make sense to add their compute power to the big picture so long as it is capable of running the software?
If the odds truly are zero (not almost zero) then what these guys did is a complete waste of time. If not non-zero then using surveillance cameras to mine Bitcoins is a big middle finger to TPTB and hardly "dim witted."