Probably depends on your computer, and what your trying to do. I have a Lenovo Flex -- the HDMI plug only works for output from the computer, not inputs, as far as I can tell. If the picture, video, etc. is on the computer, than you can use the cable to output the info to another device, assuming the other device will take the input.
Maybe some of the newer computers have "ARC" technology, or something similar, that would let you use the HDMI connection for both input & output.
I just use a USB connection, or Cloud base transfer, if those are options.