While low-frequency AC or DC current may fry some equipment, many cable TV installations will include splitters containing capacitors and transformers which do not pass such. The solution, of course, to frying cable boxes, televisions, and VCRs is RF, and lots of it.
Once having a VCR with an insatiable appetite for eating tapes, and an old empty state General Electric UHF radio of some sort with 50 watts output, I decided to set up a little experiment. The VCR and radio were supplied with power, and the coax coming out of the radio was attached very crudely to the F connector for the antenna input on the VCR (god bless electrical tape!). The radio was then keyed up. The VCR was known to have a DC blocking capacitor on its input, as I had already tried to throw 60vdc at it to no avail. However, this radio's output, at 460-something megahertz, caused the capacitor's equivalent series resistance to become very low, and sufficient power was passed into the tuner to smoke it.
So remember, if you want to fry things, use RF.