Prof Jacob explains concepts really well, but be aware that this set of videos does not cover the whole of GATE syllabus. So if you're looking for something that just covers the whole of syllabus for you, this isn't it. You'll have to supplement using standard resources.
Examples of topics missing: the whole of I/O devices, main memory organization (SRAM, DRAM, chip interfacing), control unit differences (microprogrammed vs hardwired, vertical vs horizontal and their control words), what the miss penalty looks like in a memory hierarchy (how the penalty is passed on to lower levels).
He explains the MIPS design, so you have to be aware of the analogous hardware units given in standard reference books. For example he talks about a Load Memory Data register when discussing the fetch-decode-execute cycle, I think this is analogous to Memory Data Register (MDR), which is coupled with MAR.
