I don't experience this phenomenon. I generally remain skeptical about unexplained phenomena, too, especially when they're endemic to the Internet. Despite my skepticism I can't help but wonder if ASMR is really just a way to collectively codify a set of real psychological phenomena previously considered too minor to observe or too difficult to quantify. Everyday life is rich in dull but enjoyable moments. Perhaps mass communication just offers them in a more concentrated format, much like it does with news. Information overload is a real issue, too, if not a psychological one. It's the result of an inability to distinguish signal from noise; perhaps ASMR is pleasurable because it requires observation of a small signal (like Bob Ross' whispered instructions, for instance) in a low-noise background. It's relaxing because there isn't a lot of stimulus competing for the recipient's attention but it's stimulating because it's direct.
What's considered ASMR may truly be a collection of phenomena all related to the same set of primarily audiovisual stimuli. I think it's safe to suggest that the limbic system is involved and that much of the reaction is subconscious. It's reported to be not quite but almost orgasmic, much like yawning or sneezing are sometimes described. The Slate article above also suggests some potentially Freudian parent-child reaction but I think that may just be confirmation bias; Youtube participation may skew toward female users.
It would be interesting to see what range of stimuli repeatedly produce ASMRs in those who feel them. Do gently-worded threats do it? What about calming medical interviews in foreign languages?
*This sentence originally ended "...but it's been making the rounds again." That's how the last entry begins and it's kind of an embarrassing phrase to use anyway. Calling attention to it kinda defeats the purpose of editing but now it's not redundant, at least.
**It's really kind of a curious name for the phenomena. I'd generally expect unexplained psychological responses to acquire more pseudo-scholastic and less clinical names, i.e. Morgellons. Perhaps that's one distinction between a pleasurable unexplained phenomenon and a collective delusion.