1. Nothing wrong with your computer-- there is no audio on that video. But there are some other videos on sock machines on that site that do have sound.
2. Nothing wrong with your ability to grasp it-- as I said, it looks very complicated and painstaking
But there are groups of people dedicated to these machines, websites about them, on-line groups which buy, sell, repair and rebuild them, and even a company which makes them brand new. It all looks fascinating if you've got the $ (just the machine is usually upwards of $1000, and then there are all sort of parts and pins to get) and as knittedrose said, mechanical minded. They were invented at a time when if you didn't live in a developed urban area, purchased socks were hard to come by and/or much more money than handmade ones (those were the days, huh?-- before we were buying hand dyed hanks for $30
). Even though at the time, people wore clothes many more times before washing them, each person had at least a few pairs of socks, and that's a lot of knitting. Especially considering what the average housewife was doing all day without a washing machine, dishwasher, microwave, etc. (' Course there were also no phones to answer or e-mail to keep checking, either.) So they made tremendous sense, back then.